I don't, who hasn't gone underage drinking?
A group of kids from a professional organization (let alone government-funded), under their watch no less - being kicked off a plane for something you could be potentially be arrested and withheld overnight for (public intoxication), that's something that probably wouldn't sit well with a lot of people. Namely, parents.
Clearly, your point of view is in the minority.
But I agree with you, at least. Simply, because now that I have age and experience on my side I don't think the amount of alcohol you consume makes anything more "epic" than the victory itself. Mind you, I am 40, so I completely understand that 15 years ago my response would have been different.
I've done my share of drinking, underage and otherwise...but now as someone who has crossed over and become a parent, I wouldn't appreciate sending my teenage son or daughter with his coaches and chaperones, winning a championship, and this being the result...
It has nothing to do with ruining their celebration, and everything to do with being a parent of an athlete that is on the verge of becoming elite. Permissiveness is (in my humble opinion) what is killing our society. No one is accountable for anything anymore, and anyone who sets boundaries is a hater or someone who "doesn't know how to have fun".
The party could have waited or taken a different form so no one gets in trouble. Simple as that.