A lot of times it is for film purposes. Coaches can see more and show their kids more against some juggernauts JV or second strings. More clock equals more film. You still have to grow your programs, even in lopsided affairs.
A lot of the time coaches know what they are walking in to. They are prepared for that, but you still have to get quality reps and minutes out of it. Just because you are getting smacked doesn't mean that you get out of there as fast as you can.
But, there is a time and a place to run it. If the other coach asks for it, just do it.
"What goes around, comes around" is 100% true in coaching. If you are making an effort to be respectful and trying not to show anyone up, the other sideline or bench can see that. But if you don't, every school in Texas is about to get your film