Why Would It Have To Be Mandatory?

Why would a coach at M have to make film study, treatment for injuries, weight training, etc. mandatory? Are you telling me that M football players would choose not to go to film study if it was not mandatory? Really? They would choose to go hang out and goof off? If that is the case, then we are in far worse trouble than I ever thought possible. But, I just don't believe it. If a coach says, "We'll have film study, break down the game, and look at tendencies, ... for 4 hours on Sunday afternoon." I would expect every single player would really want to be there. To imply otherwise is an insult to the university, the coaches, and the players.