I haven't had it crash my system yet, but I do run a fairly big rig. Probably in multiplayer it should be limited.
I don't think it should be limited (except for "hard" engine limits) in single player. Just ruins a lot of potential fun. Calling down thousands of pirates is pretty amusing.
I'm torn on this one. On the one hand, it is extremely damning if another player calls down a massive pirate fleet on your homeworld. Even with a fully decked out starbase, it would eventually succumb to a large enough pirate horde. And that's assuming the game will still run after you make the call.
On the other hand, it's fun that it's so damning. In single player I like to abuse it. At least don't take away the ability for us to mod it so that we can abuse it some more.