Getting the kids to come out to play is off course one of, if not the main objective. Exercise, team play, social interaction, learning a skill, how to be nice to officials and not yell them like dad does when watches TV...uh, sorry, I digress.
I do agree that those numbers could drop in the coming years if the blow outs continue. Kids know the scores and probably get ribbed in school about it.
I'd also ask myself "are they really learning to the play the game properly?" I think one that is over looked when teams are unbalanced is that the "less skilled" team or players may not have many opportunities to set an offense, get off shots, make passes, play real defense...if they are up against more skilled players. The skilled players will take away the ball more...thus limiting the less skilled players chances. If you don't have skilled players out there who can handle ball, pass and shoot, then it becomes a turnover, jump ball fest! (
see youth girls basketball)
When I ran a local league, we did a "blind draft". The players were all evaluated by all or a hand full of coaches. Each kid then was given a grade (1 high thru 5 low) based on their skills,...and put on a 3x5 card on one, the kid's name on the other side. So, if we had 5-6th graders together, we noted their school grade, skill #, whether they were potential Guard or Forward (so all the big kids didn't get on one team) and whether their parent was a coach (C) or asst coach (A).
Then we dealt the cards out, names down and built the teams. IF we had two Coaches kids on one team, we'd move them to another for same graded player. Same for asst. coaches.
I actually wouldn't allow a coach to "pick" an asst coach, because most of the time they were getting two top flight players on one team right out of the gate. The asst coach knew he was going to help out on his son's team, but didn't get to pick the team!. (see youth baseball coaches who think they are going to the MLB)