Everything (as far as I know) has been reserved and paid for at Las Vegas, especially considering Tyson's consistent advertizements for the Cube Plushies =]
The point in going to LV if you're not 21 is the exact same reason people came to Nationals this year. It's nationals.
While here, I went to the venue, cubed, met awesome people, ate food, and had a great time. All of things can be done by people of all ages at Nationals in Vegas. Just in Vegas there is the added bonus of shows as well as (if you are over 21) drinking, gambling etc.
Win-win situation for everyone in my opinion.