I have no idea what half of this means! The part about rehashes never pay off? Do you know how many people play SSFIV & SSFIV:AE? ALOT! Why? Because when people love a game that much, they love it more when the company behind it makes it better. Sure AE has the "twins" issue, but it's still a bad-ass game.
Now, UMK9 does NOT need a run button, it does NOT need any change to the core fighting engine, that would make it MK10. What it does need is a permanent rebalance, new characters, maybe a combo challenge mode to replace challenge tower, get rid of all the mini games (that weren't supposed to be there in the 1st place). Plus what I would personally like to see is an online practice mode. Where you can go online with a friend, set the options like you can in practice (infinite xray, no timer, record, ect...) and practice combos with a buddy, or help a friend who isn't so good without the restrictions of a normal match.
If we could see a game with these changes, not only will it bring in players who are still not feelin MK, it will benifit the ones who love it already.
Or maybe my ideas are stupid, I don't know