I agree with both of Oddball's points, yes indeed it's a matter of (lower) leg length mainly, and also seems to be worse on grands than uprights. The latter point might be to do with the situation of the pedals, or the thickness of the keyboard area.
I'd say it is perfectly OK to mount the piano on castor cups, e.g. these:
http://www.pianocoversonline.co.uk/pianoac...ps-c-34_94.html . You could put additional shims of wood under the cups as required to raise the instrument further.
However, this raising operation will not affect the pedal-to-keyboard base distance, which is of course fixed, it just alters the floor-to-keyboard base distance.
Also you can avoid wearing shoes with thick heels, try slippers