My only concern with ticketed/timed entry into the exhibit hall is that if reserving a ticket is the usual ticketing free-for-all, then the people who only have one-day badges could lose out on opportunities to enter the hall to someone with a 4-day badge who happens to be faster at getting a ticket.
If GenCon's going to restrict access to the hall, then the people who only have single-day badges need to be given priority on their days, especially since it seems like GenCon is encouraging single-day badges/single-day attendance this year in order to allow the most people to attend while still keeping daily capacity lower.