First off, other teams do it too.

Secondly, why allow the visiting team to give the opposing team the ability to make noise close to the field, AND keep them from pumping up their team. I was at a game when Pittsburgh was there; they had the band in the SEZ and cheerleaders nearby. After they beat us, the players all rallied in the SEZ with the band and cheerleaders; that didn't feel good for a home team crowd to have to see that. Let them celebrate somewhere else, not in OUR stadium.