Suggestion: Optional Super Weapon Cap
It doesn't really bother me that an AI or human can build several super weapons. I myself have built more than one Novalith cannon before (2 in my last campaign). I still want to suggest for Rebellion a pregame option that allows a limit to be set. I've seen other games do something like this. If disabled, the number of super weapons would be unlimited as it is now. If enabled, the player would specify how many can be created per empire.
I would probably choose 4 on some games and leave it unlimited on others. I once played a game where an AI created a lot of them and while this didn't bug me a whole lot, part of me felt that an optional limitation might be nice.