Been there,,, done that.
Madison has a great show a great impact and incredible crowd appeal. The crowd is just expressing what they feel. I was in a corps that won many shows and championships and most of the time boos were the norm... often times a winner is criticized in so many ways... Just look at the nasty Blue Devil threads that folks post to these forums,,, lots of people hate a winner especially when they are so good at what they do, they make it look easy.
Regardless, congrats to all the corps fielding this year. They work hard and you are right, Boos are so not deserved by any corps.