I'm going to go right ahead and say this: Vanilla raiders were/are probaly worse players than those that began in Wrath and let me explain why.
I'm not a big fan of writing walls of texts that most people really can't be bothered to read, so i'll easily sum it all up in a few points.
1: You watch any video of an old ''Vanilla'' Raid. You'll be watching an idiot mashing random buttons, not utilising their dps rotations in anyway (by this i mean randomly moving when totally unecessary)
2: The majority of the player base most likely downed less than they said they had - Most never even reached the last tier. What does that say about the playerbase at the time? Only a few guilds out of every realm ever saw the back of Naxx?
3: No boss had a really intricate mechanic. MC? One big add you tank and spank that spawns a bunch of adds. BWL? Like any typical dragon encounter. NAXX? Majority are again tank and spank with an add or two here and there. You name me any encounter in Vanilla that even came up to the standards of some bosses in SWP or some of the Ulduar Hardmodes.
4: Most Raiders had no idea what theorycrafting is. This goes along with Dps utility i guess. Other than the fact the majority of raiders played with Basic UI's, there's barely any theorycrafting from before BC. Even in BC, there wasn't as much as there is now.
5: There was nothing complex in balancing gear. Now days you have multiple different stats to juggle around with, meaning insightful decisions need to be made when choosing your gear sets.
So please. When all you ''Vanilla Veterans'' go around digging on new content saying how ''Its not like the good'ole days'' just keep it to yourself. Because fact of the matter is Vanilla WoW looked absolutely awful. The only reason you liked it more at the beginning is because WoW was a new and exciting concept at the time that has slowly evolved into something even greater. No one likes an experience as much as the first time, it's a fact of life. Flame or Troll me as much as you want, i'm damn proud to say i began in BC and i'm even happier that i witnessed (and completed) some of the amazing encounters introduced during Wotlk. I know that Cataclysm Raid content is going to be even better and it will only continue to improve.
-------------------------
So i'm going to post my reply here to alot of your replies since alot of them are based on the same argument. Plus i know if i reply normally my post will just get eaten up.
Firstly, alot of you are completely misinterpreting this post. I'm not saying Vanilla raiding is stupid and didn't create any ground work for the game, because even i can accept that most things start badly and eventually get better (Or start good and become even better). But the point i'm trying to make is that alot of 'Vanilla Veterans' go around saying the game had more depth or 'Skill' intended to it where if you just look at most of the encounters (Bar the same encounter every person seems to fap about) they didn't require any skill or know-how of the game whatsoever. This being true, it just means the game was played by completly brainless turkeys that thought it was amazing and when they look back to it, they're completely clouded by that naivity.
Secondly, most of you have said ''You weren't in Vanilla so you can't comment about it'' Are you kidding me? That's the most pathetic thing i've ever heard. Does that go the same for WW2? Just because i wasn't in it, i can't say it was possibly one of the worst events to ever occur in the previous century? Your going to have to do better than that. Fact of the matter is i can give my opinion, on anything i want. Bottom line, i have a very strong opinion.
Thirdly, No, I didn't just ''Watch random videos of vanilla raids'' to determine the entire playerbase were idiots. But you can very easily get an extremely clear picture of the skill levels of most players. I didn't just watch one, i've watched Hundreds. And almost every video involves the same spectacles of barely any movement needed, people clicking (I'm not bringing this argument up, but key binding is used by most of the playerbase who are in better guilds so can we just leave it at that) and finally just stupid things being done by stupid people. Alot of people have said that there wasn't a need for theorycrafting but this is an exact reason why they could have been better if there was theorycrafting. Maybe identifying when a healer would go oom, or adjusting their rotations so they didn't go oom so much. Infact one of you even said there was a prot/arms spec better than a pure prot spec, and then said theorycrafting wasn't needed - I mean come on, that's theorycrafting alone right there.
Now alot of you have said that only Mastery has been brought into the game? Not only have other stats like Haste, gem slots, profession bonuses and the bigger use of Mp5 etc been brought in, but tier sets have actually had their 2/4 set bonuses adjusted so their more than adequate. Alot of the old tier sets were silly little pure stat bonuses which was useless back then (but would be good for now considering the introduction of the importance of stats for all classes, but lets try to ignore that for a second). So i'm sorry, but anyone that says balancing gear was harder then than it is now has clearly got those ''Red Tinted Goggles'' on.
Finally, most of you have made some extremely valid points. This isn't a ''You have to agree with me or you're an idiot'' kind of thread, this is souly my opinion - which i'm entitled to; just as you are entitled to yours. But again, and i can't stress this enough, the point i'm making is that the game has evolved and become so much better in every aspect that anyone that can say or even think Vanilla was remotely better than even an expansion like wrath are stuck in a time of complete ignorance and won't accept that the game has become better.
TL;DR? ... WRATH > TBC > VANILLA