I really don't know the facts behind the waiting list, but my hunch (and it is not well grounded) is that they are using a hyper model for everyone requesting a 90 trial. The hyper model is a giant workspace that can be partitioned with up to 500-600GB. Since each trial gets 1GB, they can partition this about 500 times. To add more people, they would have to create another workspace.
Just a guess as to why. So as the 90 day trial ends, one will free up. So, keep on asking where you are in the waiting list. Perhaps that will help.