Bandages seem too easy to use in most encounters. You can have dozens of them and pop them like candy at a moments notice. This is especially concerning in pvp where an engagement comes down to bandages.
First I don't think the healing amount should be reduced, instead I think you should consider the bandages from UO as a good example of how this mechanic should work. Keep the flat heal, but put a delay on the heal. Bandages should also have a percentage chance to being interrupted making popping them while face tanking a more significant risk.