The heavy duty floor mat (Mopar brand, which I use in the winter) in my 300M tends to creep forward and up against the center console - which means it gets up and behind (and to the right) of the accelerator pedal. This reduces the amount of foot-space to the immediate right of the accelerator pedal and moves the right foot a little to the left instead of being centered on the accelerator pedal. I've found that in this position I brush against the *back* of the brake pedal when pulling back on the gas.
All in all I'd have to agree that there should be more spacing between the gas and brake pedal.
But I think that it's a manditory design criteria that the brake system of any car is supposed to be able to over-power the engine in all situations. Back in the days when you had a spring that pulled back on the throttle plate, if that spring broke you could have WOT (wide-open-throttle). I can't imagine the braks system of any car not being able to stop the wheels from turing - even in that situation.