I'd take Grizzly Hills, Howling Fjord, Dragonblight, Ice Crown, and Storm Peaks over any of the cataclysm zones. The Death Knight Starter zone was also excellent. The only max level cata zones that I found interesting were the adventures of Harrison Ford and 20,000 leagues under the sea. In contrast, the low level worgen and forsaken zones were excellent and first rate. In general, the low level cata zones were better than the high level cata zones.
While Ice Crown and Storm Peaks were both frozen mountains, one was giants/dwarves/titans, the other was all undead all the time.
It was performance resource conflict with Dalaran ... not lack of developer resources. Sort of the reason why there aren't that many adventures in the major cities; but instead combat occurs in zones away from Orgrimmar, Stormwind, etc.
Not entirely out of nowhere. His minions are in Ice Crown and some of the instances. Saronite was available in the beginning of the expansion.
Those zones were designed for characters that can fly. Also, I don't really remember whether we immediately got flying at level 77, or whether we had to be higher level initially to get flying.
Lack of plot twists applies to every expansion.
It was 10/10. Could it have been improved? Sure. But no other WoW expansion has ever been close to Wrath.