I'm interested on seeing real analysis on this (lots of rage threads with few ideas scattered around, but I think we need something more compiled). Feel free to discuss about everything, from future expansions to patches, balance, art or whatever you want to; constructively, please.
Of course, this is theoretical and from a developer perspective (which doesn't mean you should exaggerate just because you can). So, how would you fix whatever you hate from WoW if you were able to fix it?
My take on it:
-Patch production times should be shorter:
--The content we get each patch could be easily divided into 2 or 3. Focus the team on one of those parts, and release it asap. 4.3 is a good example, we've been waiting months for a raid, 3 dungeons and a daily hub, when we could have had 5 smaller patches every 2-3 weeks. Sense of progression would feel better with this system, too, letting developers advance from the most positive parts of their latest patch. Some minor expansion content like arenas or battlegrounds could wait a week or two if that means we get the expansion earlier, too. Same for the final questlines. I sometimes feel it would be better if I can't steamroll across the entire storyline on just a week, and the first zones are much more polished.
-Make the endgame last forever:
--Currently, each time a new expansion is released all the previous endgame gets screwed. Hours and hours of work for nothing, just some bored people soloing everything for achievements. The endgame should last forever, and for that, you should be able to "freeze" your level. For example, I'm 85, and I want to raid MC fairly. I would be able to freeze myself into 60 for a while. This way, endgame wouldn't die, ever, and we would have many different parallels endgames, with different rewards (yeah, T3 is useless for a 85, but you got it fighting fair in 60, and you could use it in special level 60 PvP or something). They could even expand different endgames without worrying about them getting obsolete.
Edit note: Many people seem to misunderstand this. What I mean is that you should be able to freeze your level into another lower level. For example, you're level 80 and want to raid MC. You go to the freezer guy, edit your level into 60 and get to play MC properly. I hope this is clear enough now.
-Escalation with the level:
--All abilities and talents, as well as endgame items, could work better if they escalated. For example, in line with the previous point, old tiers could escalate to become useful in lower-endgame of posterior tiers. All abilities and talents should be more Diablo3-like, meaning you get them earlier, but they're weak and grow slowly to become powerful. I'm not sure it would work well or not, but it would make life simpler and give more options, as well as help new people learn their stuff on level 30, and not 90, so they don't reach the endgame with no idea on how to play their classes. Give everything basic earlier, and escalate it with levels so it doesn't become useless (for example, I would like to run Black Temple at 70 with all my talents on, which won't be possible since MoP gives the last tier with level 90; I repeat I'm not sure if it would work well, so feel free to give extensive feedback).
-Maybe it's time to make vanilla be 1-30 instead of 1-60:
--Note that experience points wouldn't change, just how much is needed for each level. I find useless and completely stupid that vanilla, 60 levels, take less time than Cataclysm, 5 levels. With this reduction, Cataclysm could be 10 levels instead of 5. The basic example would be: WoW:1-30 TBC:30-45 WotLK:45-60 Cata:60-70 MoP: 70-80. Some classic zones could be moved to higher levels, too, so you aren't forced to level just on Outland. Replayability would improve a lot with this, and soften the pain that 60-80 is now. The rule could be 2 levels per zone. In line with the previous point, levels would give much more things, which would give leveling much more value than "just a ding every 10 boars".
-Class quests need to be back:
--Class quests had a lot of flaws, but they were awesome. I hoped a fix and an improvement with Cataclysm, but they just nuked them. Every class should have a neutral faction attached to it (most of those factions already exist in-game) and they should send everyone on special quests. 1-2 class quests each lower zone wouldn't hurt anyone, and would improve replayability around classes. Racial quests are a good option, too, but they shouldn't interfere with the major plots, just help each faction grow a racial identity outside their starting zones. Some of these racial quests could just be normal quests modified with small details for each race.
-All achievements, ALL, should be account-wide:
--When WotLK released and I saw you needed to repeat the same stuff over and over with all your characters, I was like, WTF? All achievements should be account-wide, with no exception. Everyone should have a single achievement history depicting both Alliance and Horde character progress, as well as every class progress. Making alts could become more interesting by sharing some of the rewards gotten by achievements earned by other characters. There could be special achievements for altholics, too, like "get to level 30 with each race/class" and more.
-Mentoring, now:
--You should be able to write tomes to teach any of your characters a profession you already leveled. This could be a new concept, called "mentoring". You improve your mentoring skills by teaching other players what you learned. The more you teach, the more your mentoring skill improves, which could let you write those tomes easier and/or cheaper than before. Mentoring skills could have a limit, which would require you to mentor frequently to surpass it (or else it would lower to the limit), giving people reasons to keep mentoring after they reach max levels. Mentored players would get bonuses for using a teacher, too, but they would still need to do all the process (they could save 5% of it, or more if the teacher has good skills). Having various students at the same time could improve the benefits for everyone, too. The best part of this, aside from making professions less annoying, would be socializing, something getting lost with all the raid/dungeon/whatever finders in-game.
That's all for now, I'll write more later, but I want to see your ideas to improve the game, too, so go and post them .
Edit: Some more:
-PvP, for real:
--Battlegrounds shouldn't be remote areas no one has heard about before, which can't be placed in the map, and they shouldn't be annoying open areas that interfere with PvE. Battlegrounds should be instanced versions of the PvE world. For example: pick Southern Barrens, the area around Battlescar. Copy it into an instance, and make it PvP flagged. Now put some NPCs on each base of the PvE Battlescar and give them a "Join the battle!" dialogue. If you want to join, you're teleported to the same spot at the instanced version, and you get to PvP for free.
--Or even better, when you get near a PvP-able zone, a flag appears on-screen, asking you if you want to join the battle. If you accept, you channel for 30 seconds and you're teleported to the same spot in the battleground. To get out, you just need to channel for other 30 seconds. (the 30s are to avoid fast entering and exiting, since being attacked would stop the channeling).
--This system is a goddamn piece of cake. You only need to copy and paste the terrain, and make a NPC/Screen flag teleport you there, for which you only need to copy+paste already existing code. If the terrain isn't "good" for PvP, well, then make it good by adding more stuff. You don't even need to add that stuff in the real world if you don't want to, but it would be nice if you did anyway.
Edit2: Even more:
-Mount fatigue:
--Each mount has X stamina. When you use it, its stamina lowers. If it reaches 0, you can't use it. This stamina is global for each mount type, so you can't just switch the mount. There would be 2 types: land and air. Land would have much more stamina than air, of course. Or there could just be one single type, with different mounts consuming the stamina faster or slower. Stamina grows with the character level, too.
--To recover the stamina, you need to enter a friendly town (your mount is supposed to rest there). This can be automatic, or you could need to wait a while, or talk with a NPC in the stables. The mount could recover the stamina slowly when you're walking, too.
--Additionally, there would be special food for your mount that would recover its stamina. Depending on the mount, you'll need more or less. A slow mount won't need to much food, but a fast one will need a good amount. Flying mounts will require a lot of expensive food. Or maybe all food are the same but some consume it faster than others.
--You want to keep flying forever? fine, but you will need to invest gold. If you want to save some gold, then you'll have to use ground mounts and save half of it or walk for a while.
--I think this system is pretty much perfect to fix the mount problem, but some criticism on it wold be welcomed .
-Group finder ratings:
--This is pretty important, imo. You hate a random player? ignore or rate him low, so you don't get paired with him anymore. Each player could be given a 1-5 rating from his partners. Each time he runs a dungeon, he would accumulate those rating. The ratings disappear with time (ie, 2 weeks). So, if someone trolls for 10 random dungeons, he'll have to wait 2 weeks to play again properly, because he will have tons of 0/5.