Peter and Gandalf
The problem now with AI is that it "thinks" it rules the world, whereas in reality it's crap...
In a current SP game I've seen the capitol troops of Pangea (at turn 30 approx) : 120 satyrs, 30 Hawks, and a couple Minotaurs commanders
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. No archers, no heavies, no cavalry, no mages. This army is very very crappy, if the AI had bought anything else than Satyrs it'll be that better ...
PvK,
You don't build forts ? Either you're referring to SP games or very small maps, but anyway even in these cases regularly building forts is a better medium/long term strategy than not doing it.