For amateur athletes: the players get quite a bit of value. For example, all get: tuition, housing, fees, books, meals, private tutors, access to training facilities, expert trainers, and other "side benefits."
Other players, who may not initially have the talent to go pro get access to coaching that may enable them to turn pro.
Similarly, some players are admitted to better educational institutions than they could otherwise attend. There is a very large benefit to this.
That being said, I think that was a fair bargain a few years ago. However, as the leagues make an effort to extract more and more revenue, via "additional games," the BCS, and in the future, playoffs, I think players should be compensated--especially in football and high risk injury sports. One way to do this--is to allow student athletes to benefit from commercial use of their name--in sports games and with apparel makers (where the value extends from non-NCAA talents).
I don't follow the argument as to why non-revenue sports should be paid. But I'm sure the NCAA will try to establish a market where none exists. Numerous students struggle to go through college and as state above, I think benefits currently received adequately benefit regular athletes.
Similarly, I think coaches benefit from a field that greatly restricts entry. Most coaches come up through the ranks--they play hs ball, play college ball, maybe nfl--before they can enter the college coaching ranks. Coach Johnson is an exception. He is the first coach at GT not to claim to have played college ball. But query--O'leary said he played ball, Curry played ball (pro), Gailey played ball (pro), Bobby Ross (college), B*** L***** (college), Bill Fulcher (pro) Bud Carson (college), Pepper Rodgers (college), Bobby Dodd (college), Alexander (college), Heisman (College).
There are potentially a number of individuals who strong leaders and intelligent enough to coach a team. Few of those possess the physical ability to play college ball. Further, many players with great ability may miss out on key coaching development years by playing extended careers in the pros. Further, the benefits of a lucrative career after graduating may draw many other players away from the coaching ranks (given how few make HC and how little they are paid at first combined with 0 job stability).
As a result, the pool for coaching candidates is limited, even for the specific intellectual and leadership skill set required, and they can demand a large salary.
Players are not in a similar position at the collegiate level because there skills are for the most part undeveloped and any future ability is somewhat speculative.
That said: I wish the NFL would set up its own minor league. As college football begins to resemble it's sister professional league more than any other sport, I think the justification for keeping it as is becomes weaker as a matter of equity.