I've actually for the first time managed to get into age of wonders shadow magic for the first time because this game coming out has inspired me to work past the advanced age of the thing. And I gota say, I disagree. From what I have seen, honestly most of the races don't seem that different. You have weak spear dude. Weak archer. Medium Melee unit. Unit with some sorta trick but in reality it's probably just a stronger archer with a elemental attack. Calvary. Heavy unit (which mostly seems different between races in how many movement points it has)
Sure, that's not to say there are not different races, like the shadow demons, but a lot of races fall under this and or have some very minor differences. (In particular I was very disappointed when I started a game as undead and saw I had morale in my city. They are all my mindless servants, why would they have any type of morale?) The fewer races is in my mind, if not a good thing, at least a sign that hopefully more work has gone into each one individually. I dunno how much of that is true... I guess we will see over the next week. My real hope is that they keep it different with expansions and DLC. The idea of a undead DLC with actually different mechanics is probably the only DLC (non existent or not) I've ever looked forward to.
But you know what? If you want cosmetic differences that probably don't mean anything, I would think the fact that the class system covers units will help you with that. Six Classes x Six Races equals 36 'races', more then the old games had.
As for buildings, I just gota disagree. In the old game you had a very limited building selection. This game actually looks to me like it has way more.