For starters, SC2 is not that great of an example. Very different directions/end-game goals, though I do get your point. You are correct in that the figuring out which of the variables need adjusting is time consuming..However, if you think in terms of ratio of what is known to be a serious issue vs minor issue, the game-breaking variables that needed adjustment have probably been/are being seen to in the internal beta. I believe we would be in error to assume that those guys working internally are not as observant as the rest of us in terms of the beta. So if you've noticed a problem, then there is a good chance they noticed it too, a while back. It isn't always the case, but I'm willing to bet it is more often than not. They are paid to do a job and let us hope they do it well.
Brad stated earlier that the areas of the game now that are left unfinished are not nearly as time consuming as the earlier (and completed) stages of the game. Which leaves the fluff work and adjusting of known variables. Considering the size of his team and probable work hours per week, I have full confidence that if Brad says its close to gold, then it is just that. This isn't EA , these guys wouldn't say it was ready if it really wasn't.
And to those of you at Stardock, remember..organic diplomacy!
Well, a lot of things changed from exposure in beta 1. Research changed. The economy changed. City building changed. Some of those things changed dramatically.
I find it hard to believe that those things got such drastic changes out of the public process, whereas diplomacy, magic, adenturing, tactical battles, and the modding stuff is all perfectly fine as is and in need of zero real feedback prior to release.
If they prove me wrong, great! That means the game is fun. But I'm not convinced based on what I've seen and how much it was changed along the way that the rest of it is flawless coming out of the gate. IMHO this is going to be one of those things where there is major rebalancing going on in the first month after release, once you get a lot of eyes looking at the whole game assembled and people start realizing that spell X completely dominates everything else and trying to fight against it without using the same spell is impossible.