Just out of curiosity, for the "seniors-paid-their-dues" camp, in your opinion would the same rationale apply to a college baseball team and, if not, why not?
In both cases, the majority of the team is not going to play baseball after the current level.* In both cases, the seniors have "paid their dues" and devoted years to the program. In both cases, there are summer baseball opportunities that could provide underclassmen other avenues for playing time.
*Yes, there are a few college programs where the majority of kids get drafted, but there are also some high schools where the majority of kids go on to play in college.