Heh. Another reason for there not being MP in GalCiv2 : starting position luck. Mind you, Dominions2 sometimes gives an unreasonable advantage as well ( 1 nation starts with no others within 7 or 8 provinces; everyone else has someone within 2 or 3, or is trapped on a peninsula, etc ). But Dom3 could fix that with either better random placement routines, or, worst case, people could hand-set the starting provinces.
But GC2 : normally you start on a size 10 planet ( for those who haven't played, that means there's 10 habitable areas on the planet where something can be built ). But I've started on a size _19_ planet : imagine how great a technological or manufacturing capitol there would be, multiplying 15 or so labs / factories. Similarly, having a 700% bonus site is amazing, or simply a couple of 300% ones.
And, the placement of the stars and civilizations : because the stars are generated randomly, sometimes you have a great starting position, with 2 or 4 stars that you'll be able to grab the planets for quickly. Othertimes, you're on the lone planet in a corner - and someone else is between you and the other stars.
For a SP game, this doesn't matter - players can attempt to win from a near-untenable situation, or they can start another game. Similarly, they can restart if their starting position is too advantageous. But the luck factor that is fine for a SP game, is horrible for an MP game where you want things balanced between the players. And toning down the random luck for MP, leaves more of a bland SP game.
IMO, better to do one or the other really really well. Dom2 (and presumably Dom3) does MP awesomely, even if there's perhaps a little too much luck involved, so I can understand if SP is ... a little lacking for many of us.
While GC2 wouldn't be as good for SP if it were changed for MP. Now all we need to do is wait for Brad Wardell to improve the AI a bit, improve the balancing. Just a shame I don't think he can improve the rock/paper/scissors simplicity of the tech trees and combat.