Hello,
Before I address my main concern let me WARN you: It's a rather long read. You have been warned.
Now just a small background, since it will be relevant for the topic:
Before WoW I played a few MMOs like Helbreath, Dark Ages, Ultima Online, Tesa, Ragnarok, Lineage, etc.
I've been playing WoW since 2005 (friend's account, as I got my own in early 2006).
I stopped a few times for like a month or two and once for about 5 months.
I've also played more recent MMOs like Guild Wars (1), Lord of the Rings Online, Age of Conan, etc.
And through all this I've always liked to be up-to-date on all the games I played, mainly through official and fan forums, and I've seen it all from the "OMG THIS MMO IS DA BEST EVAR AND IS GONNA KILL WOW" folks, who just end up disappointed, to the "If you do X I will unsub!!11!" crowd and many other trends, but there's a new one that really, really pisses me off: The "good times" club.
Seriously, people going "omg WoW peaked in TBC and WoTLK!" are so full of it I just feel like punching a pixie. Were you actually around when those two expansions were ongoing?
Are you saying Pandaren are bad and hated by players and that's gonna break WoW? The "good times" of TBC were RIFE with QQ in the forums over the Blood Elves, plus quite a few PvP film-makers (Hordes) unsubbing due to that and only that.
After one month of TBC people were already crying "FAIL" and saying how awesome Vanilla was and how Blizz should introduce classic servers. Now add the pissed off raiders due to the drop off 40-man content to 10~25 only. Now add those outraged over Alliance shamans and Horde paladins. Now those who completely hated heroic dungeons and having 300 keys.
Plus all the tears that the arenas generated and how much of a failed system it has been labelled since day one because X class was overpowered at any given season. Apparently the devs decide to play a new class every 2~3 seasons, thus making it overpowered. Darn.
And World PvP? What a joke. World PvP died way before TBC hit. If you were actually around in Vanilla you will remember Blizzard's futile attempts at bringing it back with the 'PvP objective' stuff in Silithus and WPL that still did not work, and ever since world PvP hasn't been much more than the casual ganking in daily/farm areas. And don't even get me started on the 'world PvP objectives' they introduced in TBC.
Enter "WOTLK". People were calling it every possible bad name and now TBC was starting to have been a good expansion after all. "Everything is too easy", "DKs are overpowered, FU BLIZZ OMG", "omg heroics are for babies", "LOL only ulduar is cool every other raid sux imma play Aion LOL!".
LFD was introduced. Do I need to go through how much QQ that generated? How much QQ is STILL generates up to this day?
Now separate 10/25 locks are like SO SUPA AWESOME GUSY, but if you recall, there was a bunch of folks crying over it since it made it impossible to have proper raiding in the least populated servers or for the more casual of raiders, due to feeling obligated to raid multiple places in two different raid sizes.
And now you come here and tell me how awesome TBC and WotLK were? Oh, please, do tell me how your first day in Outland/Northrend was and how amazing it felt and how much you loved the area and the npcs, and the quests, and the sky and the gear fairy. Give me a break. Cataclysm has many flaws, but by the time MoP is over or the new xpac is in, people will already be including Cata in the "good times" of WoW. You just wait and see.
TL;DR - Close the tab and go do something else, I said it was a long read.