What do you except of an expansion designed to revamped the old vanilla content.
We knew from the start that we will be seeing the old content with a new face or a bit redesigned, heck call it improved.
As Blizzard promised they are doing just that.
There are new things here but they are based on the old content.
Uldum, Ragnaros Nefarian, the Twilight Cult ( think of Silithius for a moment) are all elements of the the old game that have been redesigned and offered back to the players.
Are there fewer bosses? yes
Is the expansion pack short? yes
Are they using old content with modifications to offer you as new content? yes.
But honestly there was a need to come back to all of this.
Because as WoW is made, things change. And vanilla left a lot of questions unanswered ( that if you are Lore enthusiast, if not you shouldn't care if the boss is called Ragnaros or Flying Spaghetti Monster )
Ragnaros had to be defeated in his realm (Firelands)
Nefarian, Onyxia, Sinestra and the entire black dragonflight where working for Deathwing even thou the latter never showed up in game.
The Twilight Cult wasn't defeated in AQ even thou the entire Silithius zone was filled by them.
What Cataclysm offers:
Killing Cho'gall pretty much cutting the head of the snake for the Twilight Cult ( and the expansion isn't over we may see more about them)
A chance to settle the score with Ragnaros where he is most powerfull
The death of Deathwing.
Basically a follow up of the most worshiped game of all Vanilla WoW.
If you ask me Cataclysm is the real expansion for WoW, TBC and WotLK being just follow ups to the ending of Warcraft 3.
Ofc this isn't the entire of Cataclysm offer but the revamp of the darkmoon faire, even if it will be successful or not, will be just as blizzard proposed to do.
I've been playing WoW since vanilla on and off, but seen all the major modifications. The game isn't perfect but i like it.
All of the above stated i've managed to accomplish.
The grind even thou existent is reduced.
If i want to go in a heroic i click a button and a computer sorts it out. No more LF ing in chat for a dungeon no one gives a damn.
Easier leveling ups, with new quests for the 1-60 zone.
I can go normal rading and kill all the bosses, not like in tbc and Vanilla in which i couldn't go in Sunwell and Naxxramas.
patch 4.3 will offer us a raid, 3 instances ( and you have to be honest even thou you are hardcore even you aren't you will go at least 1 time in all of them) transmogrification more storage and an updated faire.
Those that rage about cataclysm. Just call it WoW 2.0. Blizzard is doing just that.