They ration out the rooms through the year. I've been in the spot of realizing I haven't booked a room until almost July, and I've had to try a few time through the week and eventually new rooms open up, but for a normal room rate, and not for the "D*con" rate.
I know the Chicago group noticed that the Marriott is remodeling, and capitalizing on the Bastardly nature of the Hyatt, and how they've been treating their guests. The Marriott has been adding bars, restaurants, and a more inviting atmosphere.
I've stayed at the Marriott ever year that I've gone to D*con, and I've always had a pleasant stay. I've NEVER been asked for a badge, denied access, or been approached by a D*con Nazi and been harassed at the Marriott... All the Marriott needs to do is open up a ball room for the costumes guests to take pictures in and I will NEVER need to step into the Hyatt, except to pick up my badge... unless I buy it on line.
The Hyatt might as well be a retirement comunity, or prison, because off all the bull you have to go through to get in, and yelled at for standing around, and NO PICTURES, and needing special access to get in.. yadda, yadda! With the Hilton getting involved to host the vendor rooms.... the Hyatt could close up and not be missed in my opinion.