Again I find that having more than three of any move is almost pointless realistically, you'll always, always only need three max, and that's just in the rare situation where you're using three of the exact same character in a fight. Sure it's a pain in the rear to be constantly switching some moves if I have more than 3 variations of a character I like to play, but right now it just makes the most sense to me.
That's why I made that lab fortress defense mode suggestion where you use lots of characters at once, cause without an incentive to have moves for more than three fighters at a time I don't see a good reason to increase the cap.