I have never seen walk-up music at a travel ball tournament, and I've been around along time. But my DDs high school does it, and its a real fun thing for the kids. Ive seen local colleges do it, and they do it in the major leagues. So I see no problem doing it.
My DD plays "Going to Fly now" from Rocky and its awsome. I think a good thing at the high school level, as your trying to create a fun entertaining environment for the fans. You're always trying to get fans there. Our school has an announcer with a PA system, he just hits the play button for a little 5 or 6 second clip as they walk up. It doesn't slow the game down, audio clips are approved by coach, and everybody smiles. Its fun.
The difference at a travel ball tournament is you go multiple fields going, and you don't have a PA announcer doing the games, you're not the home team and lots of time you're on the clock so you want faster paced games. You also have less people watching the game. Its a whole different environment at a travel tournament. It would look weird at a travel tournament, especially if timing was bad.
Curious what part of the country you are in? Just asking not accusing.
We are in Texas and every TB tourney has had it since my 14 yr old was in 8u. Not every team but every tourney. I do agree it can get obnoxious but if done taastfully its fun for the girls. If you are not having fun them what are you doing?