I think that'd be an even harder behavior for the ai to come to though, since they'd have to recognize those benefits for the other team and their origin, and then finding that taking Roshan prevents those benefits. I think that's a next step after discovering the benefit of taking Roshan.
Same argument applies to pushing and defending towers, getting rax etc. Assuming that the devs did not hardcode rewards for those objectives, then the AI surely already has to 'understand' events that impact the game in long term.
