Well I'd like that offline mode too but I also like having access to all the between games XP management via the web. I can then get this done on my lunch breaks at work and have more "game time" when I am in front of the actual console.
Still....it would be nice to save in progress as well as take over other teams when needed. Another benefit is I think you can save your offline franchise as a new file. So...if you play a game and your star QB gets a season ending injury, you could go reopen your previous save and he's not hurt! I know its cheating.....but at least its an option.