I thought about that, too, but what about the cascading effect? There are kids waiting to come in next year who may be aged out of juniors. What do they do if there isn't room for them anymore? Then if they're stuck in juniors, then there are some kids finishing high school who don't have anywhere to go because the juniors rosters are filled up.
The graduating seniors will be disappointed and pissed off that this happened, but will still go on with their lives and careers just the same as if they played the post season. But if some kids further down the line don't get their chance at all, their career might never happen.