I do take your point, but to me, those things are refinements on what they have already. Selecting 9 units instead of 4, more spells for your mages, one more type of resource and so on are definite improvements, but nothing that exciting, IMHO. The addition of water units changed the way levels could be constructed (air units, not so much), and it was great not having to muck about with roads, but otherwise it felt much the same.
Although, yeah, finding reasons for them all to fight each other all the time got a bit dubiouys, IMHO, it mostly worked. Also, having 4 campaigns one after the other from different PoV, rather than picking one and fighting the same almost identical enemy again and again on different base building levels was a big improvement, IMHO. Sticking actual characters, even if they got OtT and silly or confusing at times helped the story alot, IMHO.
I also liked what they did to the various landscapes, they put a bit of effort into giving them character, rather than the previous palette swap, though alot of that was level design.
(I thought the Night Elf motivations made sense personally "Hey kids, get off my lawn...WTF is that, come back and stand between it and me". Also, the ending cutscene wasn't great, not, but I did like the ending level, though not so much when I lose by 45 seconds.)