(lets clarify that im a 2.2k iO & MultiClass Multi Glad player - since Cata - so yes, I have an idea of what im talking about).
And once 8.3 did hit, I came back on retail and tried it... it was the worst feeling ever. The Major contents in game today are M+, Arena / pvp, Raids. I find absurd how still the game is not balanced and ALL classes are not sort of equal... equal in terms of not being ridiculous once you are Qing for a M+ without being a TOP class who does by defoult x2 more DPS than you and its not 2 times more useful... I had this feeling once I logged again my hunter and realised it was HORRIBLE on M+, this made me think that first of all I won't bother playing retail again, and secondly that for sure I won't make a new class just because mine sucks for the content I want to play.
I'm writing this hoping that someone from blizzard will bother reading this, and understanding the real frustration that its really leading me and probably a huge % of players to don't bother with wow, just waiting for a patch where your class its not totally a joke compared to the TOP ones for the type of content you like the most. Keep in mind, I wouldn't mind to even reroll, IF making a top geared character to compete, wouldn't force me to lose my entire life.
So the real solutions would be:
1. Put a real focus on making SURE ALL classes of every talent are EQUAL for specific contents. PVP and PVE % are separated, so it would be extremely easy to balance. You don't need a genius to understand how M+ for example its FULL of Rogues & DH on the top ladder. Use your brain and you will understand this is just a total depression for all other classes / players.
2. Stop thinking people are willing to reroll and reroll until the class won't be good anymore. Simply by making all classes equal, you will obtain players who are x10 times more willing to put effort and enjoy the game.
For the people who will say that this post its not sensed because obviously there are always people on this forum who love to simply point fingers and still provide 0 concrete solutions other than flaming others, I want to remember them, that talking here, there is a guy who cares about this game being decent enough to get people like me keep playing it. We all invested an incredible amount of time in WoW and I would like it to AT LEAST be balanced and stop with this no sense that destroy all my willingness to keep giving wow a try.
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EDIT: CLARIFICATIONS
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after reading some answers I've got, lets clarify:
1. Obviously I don't mean that hunter does 50% DPS compared to other classes... lets be more precise --> 30% ISH overall, that is one of the key elements why hunter like MANY OTHER CLASSES can't enjoy the game.
2. If you enjoy the game like this, don't bother commenting, go play. Im talking for the people that obviously don't feel in the same way as you do. I'm happy for you, if you like the game to be unbalanced and not being able to compete at high levels just doing the "best as you can" with your class.
3. IO score, gives an idea of what lvl you did compete in the game on the M+ content. Its better than nothing. Generally talking, its very efficient. All the people that say that it is useless, are just players who don't know what they are talking about, or who are mad because they can't get it high enough for the M+ lvl they want to join. Don't complain the score, argue about the people that don't understand that a guy with 2k iO CAN prove to be worth more. It has nothing to do with the score itself, it has to do with the mentality of the PLAYERS who think that a 2k player is worst than a guy with 2100.
4. Seems most of the people didn't get the point of my post, but its normal, as I said I expected it I'm one of the players that points out the fact, it's very unfair to set for a specific content like M+ some classes FAR above everyone else. It makes TONS of people to lose all the motivation to keep playing. It affects the majority of the players when they try to do QUE and ENJOY the game. On top of that, WHY progressing when your class will be considered too crap to compete at high lvl content? My points are VERY solid and easy to understand, if you don't, no wonders why this game is at this stage. We are not playing LOL where you must play another 20-50h to master another champion... we are talking about a game where you MUST invest HUNDREDS of hours to GEAR and lvl up. Thats why the balance on such a game its vital. In LOL I can simply change champ and deal with it (they must balance 120+ heroes...)