I see it happening more and more for their final seasons. I do not like it, because it seems like you are letting the team down for your last horrah with them. But at the same time if you get hurt you potentially could lose out on loads of money. However, I am more with the former.
I do not see it happening with the playoff teams but with the other bowl games it will probably happen more often. Seems if you are in a big bowl game than being a part of it is important or at least should be. Another chance to show off your skills against a good quality team. Most of the time anyway.
There are loads of bowl games though. I do enjoy watching most of them but really the guys that are going to sit out are those with talent that can potentially go to the next level. So it would likely be players from more elite programs with somewhat, in their minds, disappointing years.