Earlier quoted context omitted.
I have played both games and a fan of both. Starcraft is definitely more complex than AoE for AI development and that's why the researchers must have chosen it. The complexity of AI depends on how many potential decisions you can make at any point of time. Here are a few reasons why: 1) Starcraft races have completely different build trees and different advantages. This has a large cascading effect of early decisions…
what do you mean exactly by "The Starcraft map terrain is hierarchical"? do you mean there are more choke points?
Also, if units are walking through a valley, units on the high ground can shoot the ones on the low ground but not vice versa.