ToME: the Tales of Maj'Eyal

If the AI could ask their allies to make a path for them to attack when they couldn't otherwise as a group they'd be a lot better. Perhaps only tactical ones would talk though

Melee bosses can already move their allies aside to get to you, and I can't think of many minion-based caster bosses other than the Master, who reasonably doesn't care. For common enemies, though, I don't know that I would expect it to be that organized, especially if they aren't intelligent enemies. I could maybe see this in some of the orc prides, but even there it doesn't seem to be much of an issue to me, since most of them are heavily themed to caster or meleer.

Also, if the enemy could do this, then I'd expect minion-PCs to be able to do it, too. Why can't my summoner tell his minotaur to move over so the flamespitter can get a clear shot?

That's the thing, the minions themselves would communicate

Enemies having perfectly optimal AI degrades strategic options, rather than improving them, in many cases.

This is one.