Not a huge deal to wait through the marching band but why make fans sit through it? There is almost zero entertainment value for most people in the stands, other than sitting there hoping one of them accidentally trips. Some marching bands are fantastic and really do add to the atmosphere, but most do not.
It was entertainment back in the day. There are now a hundred other superior forms of entertainment that could be brought in. Dance teams, local artists, competitions, etc.
If you like marching band, I respect that. Go to a marching band competition any time you'd like.