Why?
What's your valid reason for making a player sit a year if he decides he'll probably never get playing time and football is his dream?
If you're a good welder but the company you're currently working for has you in the paint department, and says it's not likely that you'll ever get moved to the weld department, but you really really like to weld, should you be prevented from welding for a calendar year if you decide to change jobs?
And save your key strokes if your gonna say, "but it's not a job to play college football!!" College football players are in 2021 are there for one thing, and that's to provide a service. That service is playing football, and their payment is their scholarship (for now).
And if you believe they're in college just for an education, then why do you give a shit what they do with their football career? If I decide I like Iowa better than Iowa State, would they make me stop going to college for a year because I transferred?
Oh....I don't have a problem with it at all in terms of the player making the move. It's the way it is. The rules/etc. had to change to accommodate it all. The nature of the importance of it in some player's lives has attracted more and more players. The importance of the value of it for certain players exists now that didn't 20...30...40 years ago. I can count on one hand the number of years that the Super Bowl is older than me. And I'm not 'that' old.
Masterlock didn't start expending their entire TV budget on one football game until many years later. There was no Arena League, XFL, CFL, or USFL. A bunch of the current teams didn't even exist. Stan Kroenke could have moved his team without having to pay nearly a BILLION dollars to a bitter city. There were about 5 college football games a week you could watch on TV up through the early 80s. Now you can see every single game just about. Every team can be relevant nationally. Every player. It's all scattered across two 24/hour sports networks....and 24 hour networks dedicated to most of the larger college sports conferences.
So, even if you don't wind up playing a few years as an NFL back up....all those properties need coaches, commentators, scouts, athletic/team/player directors, trainers, writers, you name it. Plus high schools. Even for a minorly successful college quarterback, there's tremendous value and opportunity beyond working at an in-state bank/insurance company. Even autographs and appearances can monetized at much greater value than in the past.
I don't hold it against the players one bit. It's the way it is. I just kinda wish it weren't, but acknowledge if that option didn't exist, it would be horribly unfair to a lot of people. And all those who benefit from their success (teams and players, broadcasters, advertisers, construction workers building stadiums, and people who manage facilities, the people who make/service the products that are being advertised). No single person could make a pencil.