I don't mind a run button but I have trouble with one button doing a ton of stuff. GRFS's roadie run button also is used for entering cover and vaulting cover. I end up getting a good amount of erroneous...well unintended actions because of it. Obviously it's the operator that needs to improve but it does induce more things to manage along with the plethora of additional actions that are becoming available as games evolve.
THEN going from game to game and needing to change your fingers out because the control layout is different. That muscle memory starts to forget!
Not a problem when you get good time with one game.