Let me start by saying that I'm pretty happy with the game so far. Sure it needs to be better balanced, the UI can need a little polish etc. But SD has shown that they will deliver, just give them some time. Why? Because the team probably did not have another choice. They had to release it now.
The rest of my post is speculation about why the game was released now. Just by reading the journals, forum posts and connecting the dots, I come to the conclusion that Stardock probably had no other choice than releasing it now, and finishing the game afterward. I'm pretty sure the developers can't comment on my speculation. I'm afraid we will only know what really happened when reading Brad's memoires 
Yes, I think it was rushed to meet the august 24 time slot. This was clear in the 3 months before the release. People on the forum felt it, it would be too soon given the type of changes that were made this late in the development cycle. Sure it's an experienced team and the changes and fix list was huge every time it was posted. Yes, you can do a lot of development in a day if you have a well-motivated team. But you can't do a lot of balancing, polishing, beta testing on a lot of different hardware configurations in a short time. This type of quality assurance and verification takes a long time. You really can't rush or skip a big in-the-field beta test with the gold version. There clearly was no time for that.
We don't have to try to convince SD that the game was rushed and needs more polish. They are software developers (as I am), they know that, but they probably had no other choice. With all the experience that they have, I cannot imagine that this was a bad case of misjudgment. No way. The next time slot, for a release after august 24 was february 2011, as SD stated. I think it's likely that they couldn't wait that long. They probably needed money now to be able to continue with the game. Banks aren't very eager to lend a company money these days and you need a lot of it to be able to hold together a middle-sized team for six more months.
Is this a bad thing? No, I would have done exactly the same thing. I don't feel screwed for buying the game either, because I know Stardock is not trying to steel our money. Heck no, they want to finish and continue developing something that they want to be the best TBS game ever!
The game is fun to play already, and the potential is very eminent. I have a feeling most of us want this to succeed so badly, we will support the team all the way. The game-press wants it to succeed (except maybe one or two journalists that bear some grudge). Most are waiting with their reviews to give Elemental a bit more time. That is not very common, it shows they want this to succeed.
So take your time, team. Fix the important bugs first, and then let the fun. Let's make this game better and better!