Yep, AI's don't typically Last long in PBW games. Pretty much they just serve as buffers between the players, and easy ways to pick up tech and planets when they inevitably surrender.
A lot of PBW games don't even bother with AI players. If they do the real game doesn't really start till they are gone. At least in my experience.
And I didn't mean bad in the literal sense. It's just a game after all. The best PBW games are the ones that start to feel like a story after a while. And every story needs villans.
Geo