Because for the most part the lineup is already set before the year starts, Trent will be there next year mark my words.
Some people still are unaware as to how the invite system for Vegas works, this is no longer a motorsport but a entertainment business. If enough people demand to see a truck at Vegas, you think FELD will ignore it? Granted there are people that turn down invites because the money they would make would barely cover travel costs or fixing up the truck after the show. Just as much as you want to complain about people complaining, they have the right to voice their opinion on the matter regardless.