AI would definitely improve RTS games, aswell.
I remember playing against 7 brutal enemies in Red Alert 2; the computer players actions were like clockwork; they were so predictable, that I'd already have a countermeasure for everything they did, before they'd even done it.
They'd send the exact same amount and type of units at regular intervals, they'd always follow exactly the same path to your base, they'd always target exactly the same things etc...
At the end, I would end up getting somewhere between 2000-4000 kills, and about 0-5 losses.