Yes, football is really important to colleges. Here are some of the reasons why:
1. Alumni care about sports. The sports teams help us to feel connected to the schools we attended, and when the teams are winning it can help us feel proud. They also make it easy for people to sell us a lot of licensed merchandise, and the connection they help us feel makes it more likely that we'll donate money to the school. Football brings in a lot of money from ticket sales, licensed merchandise, donations, and so on. Basketball brings in enormous amounts of money.
2. Prospective students care about sports. Not all of them, but for a lot of people, part of "the college experience" is football games on Saturday afternoons. Moreover, kids who know about colleges at all are likely to know about those with sports teams. They may grow up wearing t-shirts from a local university, or a university that a parent attended, or whatever, and therefore winning teams can help recruit kids from a young age.
3. People on campus care about sports. The football programs are already in place, and if you started talking about dismantling them, or cutting back on the amount of money spent on them, you're going to upset people. Did you see how upset UPenn students were when Joe Paterno got fired, even though there were good reasons to fire him? Students and professors and administrators and other university employees -- again, not everybody, but a lot of people -- feel an emotional connection to their teams, and the suggestion that the teams might be eliminated would really upset many, many people. If there weren't already football teams at so many campuses, people on campus might not feel strongly about starting teams. But eliminating teams that we already feel so strongly about is a whole different thing.
And winning teams are even more important than losing teams. There are real downsides to that: you might be interested in reading a book called "Scoreboard, Baby" about one year in the University of Washington program or, for a look at some high school football players who thought they could get away with awful behavior, "Our Guys" about the Glen Ridge rape. It addresses some of the real costs to human beings that can result from schools' efforts to build and maintain winning football programs. That includes costs to athlete/scholars, who may end up on campuses where they don't have the background to really succeed in classes and where they are dealing with all sorts of responsibilities to their studies and to the team, and who may end up graduating without any prospects to play professionally but also with an inadequate education. There are also harms to individual players who sustain relatively minor head injury after head injury and can end up with significant brain impairment, and who are at risk for a number of other kinds of injuries. But there are also advantages to schools of taking the programs that already exist and making them as likely to win as possible. And that means that players who can help a team win are very valuable to colleges.
If you go to UCLA and achieve something significant academically, the UCLA alumni are a lot less likely to know about your achievements than about how the football players are doing on the field. Prospective students are unlikely to hear about your achievements unless the school chooses to showcase your work on the admissions-related part of the website. And many of your schoolmates and even professors and administrators and other employees are likely not to be even able to understand your achievement. You certainly won't be building a legacy that lives on long after you're gone. Schools absolutely recruit top scholars, because a reputation for academic excellence really helps the school in many ways also. But football connects to all of our emotions, and that can be much more powerful. It absolutely does mean a lot to most or all colleges with football teams.
And I do think sports helps humanity. For one thing, I think the sense of connection with other people can be very valuable. Second, I think that whenever anyone strives for excellence in almost anything, that's important to humanity. And finally, I think entertainment is important to human beings -- not necessarily as much entertainment as my cable company wants me to absorb -- and that watching games is therefore something valuable to many people.