I think people are overestimating how much of a set-back this is. Square Enix may be bad about keeping in contact with their audience, but they're not stupid. They know that putting out an incomplete product would be catastrophic, and they wouldn't be pushing the September 22 release date unless they were confident with their ability to make that deadline.
Further, rough starts are fairly typical of MMORPGs. Most all of the titles released have rocky beginnings while the developers work out more and more bugs and refine game balance. The nature of the multiplayer experience complicates things making a perfect release near impossible. SE's plan to release the game eight days early for the collector's edition is a good move towards mitigating a number of the server issues which plague the first few days (or weeks) of release for most games. By releasing to a limited crowd, they don't have to deal with everyone trying to sign in right on the same release day and have a while to make adjustments before regular release.
We were spoiled by FFXI's release. Because the game came out a full seventeen months after the Japanese release, American audiences didn't have to deal with these types of problems. I wouldn't worry until the game breaks out of the box (which I doubt it will do).