I think this is a great point. I just don't know if the build you guys are working with allow this.
I have never had the urge to edit player ratings while I am playing my franchise. As another poster pointed out I just edit and save them before going into franchise mode. Once I am past season one it really becomes my universe and I leave it to the progression system/injuries and performance to determine future ratings of my players.
Would it be cool to be able to edit in-season? Absolutely. But if it would create massive crashes and bugs no way.
It is very appreciated though that you posted here to get some fan feedback. I hope 2012 gives us that overhauled immersive offline franchise mode we are all pining for.