The only reason people still go about vanilla and tbc (the jokes that they both were) is nostalgia.
In fact it's gotten so bad that there are people who feel nostalgic for old content when more than two thirds of them have never even played it.
My first character was back in vanilla,an orc hunter,T2 just came out and naxx40 was nowhere mentioned yet.
I stuck with retail right up to Ulduar when i quit.
Vanilla and TBC were not the hardcore days,raids were not mechanically more complex than they are now,the reason why it might seem so was exactly the same reason why raids nowadays seem to be too easy. Addons.
You cannot develop a hard raid in this day and age when every single thing can and is tracked by addons.
The old saying ''Don't stand in fire'' comes from vanilla when addons could not properly,if at all track boss aoe or certain spell trigers,you did not have DMB to warn you,so you had to pay attention by your self.
Go and watch any old raid that was there before t4/5ish,if back then we had the tools we have now,AQ40 would have been on farm status for 50% of WoW guilds within days,same for naxx40.
Anyone who says that back then raids were harder and pvp was more fun ,has never played neither of the expansions,or is so full of nostalgia that he is about to blow unicorn dust out of his rear end. What we have now is a direct result of actions taken by players them selves,DBM was not made by blizzard,nor was gladius,power auras,atlas loot,or any other tool that can track and display signs/warning/information about every single thing in the game.
The reason why horde got paladins and alliance got shamans? players complained,same for homogenization of every other class and spec. If enough of us complain,Blizzard will obey.
TL/DR: It's not the raids that ever got any easier,it's the tools made by players that got more and more advanced to a point where providing any challenge within the game became near impossible.