I watched a lot of football yesterday, and every time someone on the defensive end made a stop, they celebrated. More often than not it was not a spontaneous, having fun celebration, it was a pre-choreographed 'routine' that the player obviously did every time he made a stop. So the guy's not really happy and celebrating with his teammates, he's making a concerted effort to show up the other guy and perhaps get a video of his "celebration" replayed over and over.
The same on the offensive side. When a guy gets a first down, even in the first quarter, more often than not he has to draw attention to himself by making the "first down signal" instead of just getting up and going back to his team.
But if he scores a touch down, once again - more often than not the player totally ignores his happy teammates attempting to congratulate him, he's got his pre-choreographed celebration routine to get through. Which means, again, it's not about his team, it's all about him showing off.
And kids being impressionable, as we know they are, they're going to learn that ignoring your teammates so you can show off to the fans is the way to go.
And that's why celebrations should be curtailed. It's not that the NFL should be the No Fun League, it should be the "fun" league, not the look at me as I gyrate around like I'm on the dance floor instead of the football field!