HFA is a big part of the real game, but it's current implementation is not mimicking real life. It's gamified, and not in a way that I think is good.
-Hand signals exist for audibles in loud environments. Teams practice for loud environments, but this isn't accounted for, at all, in EA's game.
-Players don't forget their route assignment and especially don't forget that they called a pass or a run play (from the call in the huddle) as the current generation of CFB games would have you believe (ie: wrong play art). Crowd noise is not wreaking havoc in that way.
What should HFA be?
-Increased false starts
-Audibles are possible but perhaps a limited selection of audibles to match a simplified offense in the noise, and OCCASIONAL missed assignments from the audible (though this should probably exist regardless of crowd noise). It might even be appropriate to have audibles take additional time to get right at the line of scrimmage.
-Delays in getting the play call in (additional play clock clock runoff out of the huddle because the QB couldn't hear the play call), potentially resulting in delay of games
-Possibly an attribute penalty for players who are not good under pressure.
The current iteration of HFA in the CFB does not represent a simulation like experience and it is just an oddly implemented one. Just think about it. One of the "features" of HFA can be 100% overcome by memorizing your playbook. I'm of course referring to incorrect play art and receiver icons. No other feature in the game can be 100% overcome by "skill". There are far more accurate ways to represent HFA, and while I want the challenge and simulation experience of HFA, I would rather not have it in the game at all than the current version so a menu toggle would be nice.