The AoE push happened in WotLK, it was just enhanched in Cata.
For me its vanilla > TBC > Wotlk and it stops there. I'm a huge storyfag, played all of the expansions but couldnt really "get into it" after Wotlk (not saying everything in wotlk was great, only the story part as a direct continuation of wc3).
Yeah it was hard for me to see the book close, so to speak, on the WC3 story. I remember during Vanilla and TBC there was a lot of theorizing about facing Deathwing at some point, but ugh... Dragonsoul raid was such a letdown. I will also say it was cool that Cata finally fleshed out some areas of Azeroth that had been placeholders for so long such as Grim Batol and Uldum, although I always expected Uldum to be another Titan base/facility and not a copy of ancient Egypt.
Uldum, in the Blizzcon preview before the zone was made was meant to be repository for ancient Titan weapons protected by mystic race and it'd become the major struggling point in the war between Horde and Alliance. I guess it did happen in essence, but I doubt anyone was expecting short quest line of the mystic race while rest of the zone was dedicated to Indiana Jones.
And don't let me get started on Grim Batol. They really fucked that shit up. Aside from the pretty amazing grandiose theme, that place was bullshit. It should've been at the very least a proper dungeon crawl into ancient dwarven city that has been part of Warcraft since the second game in vein on Blackrock Depths. Multitude of levels, city-like layout, different sections for different purposes. Not some damn zig zag round we go zig zag design to hide the fact it's straight corridor.