That was months before this weird explosion of interest in Ni no Kuni. Now that the demo and reviews are out, people reaalllllly want that Wizard's Edition. I think I've seen at least a few hundred comments like "I wish I could've gotten a Wizard's Edition...." since the preorder closed and now that it's available again at a specific time... who knows what will happen?
Also, they had set a time limit on the preorders back then so after August 31st, no more orders could be placed. However, in honor of PAX or w/e they extended it to September 4th.
My worry is that their site will not be able to handle the traffic, I suppose. Most sites NEVER prepare themselves for things like this so things tend to go wrong even if it's only a hundred users or so.