Healing That Doesn't Always Heal

Here's a little something to think about: what if we changed the wording of the Cure Light Wounds spell, and the other healing spells to match, so that it said this:

Cure Light Wounds: Removes one wound from a character, plus up to 2-7 hit points of damage. Has no effect on characters who are not injured, even if they have suffered hit point loss.

How would that change the game?