For the kids maybe, or just to lighten up the environment.
Recently, I went to a minor league hockey game here in Des Moines (these are college age students playing as amateurs and hoping for a shot with a NHL minor league team) and after every stop in the action, something would play on the video board, or a pump-up song would begin for a few seconds, and gradually fade out etc...
I'm not saying these are bad things. I liked it for the most part. It can take away from the game experience though, but in this case, since it was just minor league hockey, it made the experience better.
But I guess the big point here is that sports (professional or not) is about money in the end, and we will probably keep seeing a slight rise in the 'sideshow entertainment' type stuff, as I'm sure it makes fiscal sense $$$$$$$$$$