Its not the solar systems that arent at all realistic, its not the pirates, its not the lack of varsari. Its how empires are managed after defeat.
I dont know but after I beat 1 empire in a larger game they arent actually defeated, the ai just shuts down. They dont lose anything else, nothing switches control, nothing else is destroyed but I dont know how a defeated empire still manages to maintain starbases and titans, not to mention fleets and numberous planets.
I dont know my only suggestion would be to have everything start decaying post defeat, I should not have to throw huge fleets at defeated planets. If not everything it would at least make sense for the starbases, titans and possibly even the capital ships to decay or self destruct after a certain time.
Also, I dont know if anyone else is getting this but the ai canbe defeated rather early, relatively. Even on capital or flagship victory the ai gives up long before you ever get them.