The number doesn't matter at this point. The more games, the more chance to catch a game during the holidays. I would make one rule change and that would be to allow non-bowl teams the same amount of extra practice that bowl teams get. The worst teams need the extra practice more than the good and great teams...
The main thing I hate about the current bowl season is that too many fans think those games matter. I am tired of whining about draft-eligible players not playing or about games where one team obviously doesn't give a shit. Outside of the playoffs these are exhibitions. If you want to exchange more football for the prestige of getting a very limited number of bowl invites, then accept that some coaching staffs don't give a damn (maybe even your own school's) about a potentially meaningless game. For Texas last season, the bowl game was very important for morale, but this year Herman may not see a bowl game (in the unlikely event we don't make the playoffs, show me a loss) as having the same symbolic value and we may not see our best game on the field.
The new redshirt rules will also likely see the quality of play decline as some teams will throw their freshmen out there in droves to get them some action and see how they perform under the lights.