Q u o t e: You're forgetting that hardware technology has also improved by leaps and bounds. Also, you wont be able to see more than probably 100-200 units on the screen at a time simply due to the camera angle.
Well, I imagine it would depend on the monster. You could probably fill it with 1000 fetishes. Or 3 siege beasts. But what is important is winning a fight on a huge battlefield with all kinds of nasty things trying to make you become nourishment for plant life.
No matter though. If you take 10000 actual monsters, plus an objective, mix it all that up in a shake-and-bake bag, throw in an army of your own, and you have a dish worth eating.