To get back to the original question, I have played with ideas that concern Privateer, since that's the WC game I enjoyed most.
First of all, it would be nice if you could broadcast a distress signal, and depending on the system you're in, it could attract merchants, pirates, Kilrathi, confeds or militia, and depending on your alignment, they could either help you or join in trying to destroy you.
As other have said before about Privateer, getting a Kilrathi ship would be nice. Maybe you could help them in destroying the Perry Naval Station?
And this is not exactly an enhancement, but another expansion pack for Privateer would be great. My idea for that would be that the Steltek return after they notice that there has been a significant increase in use of Steltek technology in the Gemini sector.