I agree with you that there isn't a single right or wrong answer. But I think the benefits of the system go a lot further than what you mention. I already detailed a lot of them in post #67. Players who are not destined for meaningful NFL careers benefit. General college populations benefit. The teams benefit by avoiding having to take players before they are ready to play pro ball. And that's not even touching that fans benefit.
I'm not sure how the players not destined for meaningful NFL careers benefit, unless you're under the ridiculous impression that elite football players who don't care about school are still getting an education in college. Also, that strikes me as way too paternalistic. "Your parents and trusted advisors will steer you wrong ... only the NFL knows what's best for every 20 year old kid!" I don't understand how general college populations benefit. Because a tiny handful of players who are good enough to go to the NFL are forced to remain in school? I don't think that would have a any impact on the health of the college game. Not that I care- I'd rather do what's best for the kids directly, rather than do what's best for the schools that are supposedly passing along those benefits to the kids (just as soon as they get done paying Nick Saban another $5 million salary to coach kids who are playing for free).
Sure, the NFL teams collectively benefit ... but again, I don't care about them. If they're not smart enough to properly evaluate talent and potential, why should we protect them from their own incompetence by not letting them pick sophomores? You see this nonsense all the time, most notably from NBA owners. They actually had to create max $ and term contracts, because they're too stupid to properly value star players. Protecting people who suck at their job isn't a "benefit" I care about. Certainly not at the expense of even one Marcus Lattimore or Nerlens Noel.
Not really sure how the fans benefit either.
Seems like the fans benefit by having the best players on the biggest stage.