To be fair, it is still in beta, so we can't complain too much that MP is not working, just highlight the fact and hope its ready soon. If its not ready on release we can complain big time as it was a feature clearly promised in GC3.
Having said that, I too am interested in playing GC3 MP, perhaps just on tiny/small maps.
I play a lot of Dom3 and now Dom4 MP, in fact probably a 100+ MP games, great fun. Those are PlayByEmail which works very well. I assume GC3 will be real time MP? Its interesting with GC3, tiny and small maps could be played MP in a single big gaming session as its a pretty fast game. But larger galaxy types, particularly mid/late game would probably suit PBEM on a 24hr turnaround server like Dominions 4.