One of the 2 main surfaces (Clay or Hard) will always have an advantage over the others. If US Open switches to clay, clay tournaments are gonna be more numerous than hard tournaments because this shift would imply an extended summer clay season. If US Open would switch to grass, a better balance would be created, but grass is the most expensive surface.
Obviously any player would want his favorite surface be more wide spread than other surfaces.
Slasher, do you have any idea what the extra cost of grass is? How much more cost accrues to Wimbledon than to French Open and Australian Open?