I think everyone is missing the fun and spontaneity that this could bring to the parks.
So let's say a guest enters door #1. A CM will then be there to offer guests the ability to stay in door # 1 for a chance to advance through the queue or trade in door # 1 for either a new door or a box (that can be brought in by a character for the added excitement). The box could contain an immediate bump to the front of the line, a Mickey Bar, a t-shirt, a special seat for fireworks, socks, a bounceback offer or absolutely nothing!