The multiplayer code is over a decade old, and so not only are the AI difficult to play against in a fun manner, other people are difficult to play against for frustrating technical reasons

This is making me feel old. Me and a few college mates had a SMAC multiplayer game running for the better part of a year. If someone told me now that I could have a multiplayer game experience by taking my turn, zipping up the game file and emailing it to the next person in the cycle, I would laugh in their face.