I would imagine there are a ton of difficulties in this kind of game. Dealing with the school is one thing, but dealing with rosters and players is a totally different thing. For instance, in the NFL, the draft happens in April, and the new rookies are made between then and the release of the game (Typically August).
How can you put freshmen in the game when they don't arrive on campus (some of them) until June or July, when the game likely will come out? Unless you started trying to go to their high schools after NSD is over, I don't think you could. So, a freshman wouldn't be able to be in the game until their sophomore year, one would guess, unless they're an Early Enrollee, which not all can be.
I'm not sure why a player WOULDN'T want to be a part of this, even though the payout isn't going to be much. The nostalgia of seeing yourself in the game, which for many, would be the only enshrinement of their involvement in college sports, would be great.
I'm looking forward to seeing what everything looks like. I, like others, just hope this game won't be riddled with microtransactions, though I'm sure it will be. Hate those things. Buying the game should be enough.