Most are entered early-well before they qualified... The hotels are booked, travel, etc... To cancel all that after they qualify would be pricey... Not to mention the havoc that could cause by pulling out of an event late (for instance qualifying the week before the next event)
the national and American divisions are a crap shoot since there are a lot of teams in those divisions and very few bids for nationals. the open division has a max of three bids, depending on the number of teams registered for a particular qualifier.
Many larger clubs make qualifying for Junior Nationals their goal for the season, so they hedge against bad weekends, injuries, etc. by entering many qualifiers so that they have more than one chance at getting a bid. So if a team qualifies early, they are still committed to playing, as someone else said, they can't cancel their travel plans etc, so they go and play. The competition, especially in the open division is very very good. The competition drops off a bit in the National divison and even more in the American division.
Engineering is my vocation, volleyball is my obsession.
That's quite a stretch. The number of teams that play in multiple qualifiers after winning a bid is pretty small.
Losing 2-3 teams in an age group shouldn't make or break a qualifier.
More importantly, airlines aren't going to refund your money because your team already qualified. Any team that floors to a qualifier spends way more money on airline tickets than what goes to the qualifier itself.
Paying $37 for said fare and a small drink with to much ice!
Watching someones DD rage on their unwitting mother about how unfair it is that she only plays three rotations while waiting for their Maui Waui - and their mother asking "whats a rotation".... PRICELESS