I haven't read the article, yet, but this will allow everyone who wants to go a chance to pre register. There are 4000 places contracted for the conference, don't know if they can get more in.
I think there will be good demand at GR, others think it is harder to get to, and not as many people in a short drive. This will give a count on the true demand, and be fair (remember all of those that said it was not fair that they had tok be at work and could not be on line?). People won't give up due to a crashed web site or the conference filling up too quickly. The wait list will be there. Also don't forget that just on this forum they were several tickets offered up by folks who had last minute conflicts - so if you have will there is a way.
My take on it is that the AHA and the GC listened to the members and made adjustments.