I am worried
All that you have said makes perfect sense. However, this is just your preference and taste. Other people have other preferences.
I am fairly certain that here in GalCiv 2 we have a SP preference oriented community. Thus I would expect all those replies. However, as GC2 does not have MP, its no wonder there are not so many MP fans here.
I completely agree that playing MP games on the internet with strangers is often a bother and not very much fun. To make that viable, you would need something flashy and new. Civ4 did that to some extent, but not that well either.
For me, the MP option is more for LAN-parties or online games with friends, where you spend some hours (or even nights or days) but always have the option to save the game and come back at a later time and resume at the milestone you saved. That really is extreme fun and very challenging.
And I have yet to find a game where the AI is flawless. All the TBSGs I have seen, especially the space based ones, have major AI issues such as attacking planets, defending systems, evaluating threat and so on. Sometimes it is better to cut your losses, sometimes it is better to stay and fight even if you know you will lose. With the AI its just bits and bytes, 0 and 1. And I will be very surprised if the AI will be as challenging and devious as another player...
Many games just give the AI races a resource bonus at the beginning to head them off. That is lame. Then in many games the AI will not even colonize correctly.
I am not in beta so I do not know if those issues are true, but I wager some of them are, if not most. Especially in the endgame, when you have big fleets running around, the AI always seems to be overwhelmed, overworked and acts erratically. A decision to lose a planet to a big fleet while sneaking up on some important system in turn I have yet to see in a game. Even if the AI by chance would do that, if a system is threatened it usually breaks off what would be a perfect move to protect the system.
You can only do so much with an AI. You can experience infinite scenarios with a player.
And that is really my grudge. Having played a couple of games, you will know how the AI reacts to certain situations and begin using them (the diplomacy and demand tribute is just one example). With another human player you can never be sure.
Now, to have a solid AI *AND* an human player would just be heaven IMHO.