Pressing the button enables all simulated power on the FSX runways with best friction values all the time and no dirt, moisture or other things simulated.

I you would switch from on-off buttons to e. g. pedals, you could alter this behavior somehow and make it more realistic. Currently, with the button, you are going digital with on-off braking. Hard to simulate a real reaction then.
I doubt that the real pilots jump on the pedals after touchdown like this key press simulates (going from 0 to 100% in milliseconds), so at least the beginning of the process would be far more gentle with pedals.

There might also be some addons around to simulate runway conditions.