I don't think the raiding has changed much, I personally always found raiding kinda easy from my POV as a healer. 5 Mans are WAYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY easier now. Back in TBC unless you completely outgeared the instance, to complete a 5 man you had to cc multiple mobs in each pull and have a kill order, for example one mob sheeped, one mob hunter trapped, another mob sapped then you would kill skull first and then X or something along those lines. Now when you do a 5 man its just the tank runs in collects the mobs and everyone aoe's them down and you move on. BUT in saying that, I honestly think if people took their nostalgia out of the picture they would not be able to put up with having to co-ordinate CC and proper kill orders just to complete every single trash pull and would just cry for nerfs so its easy like it is now.
The worst part of the game in MoP is the way gearing up works.
In TBC you could farm heroic dungeons and get gear from there, then also buy a tonne of gear with badges (now points) and be easily ready to raid entry level raids such as kara and whatever. In MoP to gear you had to go out and complete dailys for over 9000 different factions for THE REST OF YOUR LIFE in order to unlock the ability to use he same points (which you also had to farm up ontop of the other farming) in order to buy any gear of the entry level gear.
NOTE: In Wrath and Cata I had a max level of every class and all of them had atleast one spec that was in raid gear, most of which also had a raid geared offspec. In MoP I have 2 level 90s, one is in pre throne of thunder gear, and blues for offspec, the other is in blue pvp gear. All because the way the gear was gated really put me off the game.
There is probably some other things I intended to talk about but it's now 1:30am and I need to goto sleep as I will be getting up for work in a few hours and im already struggling to keep my eyes open. Goodnight