I've had other healers complain that I DPS a lot and make them do all the healing, except those tend to be the healers that cast Cure whenever the tank takes even a shred of damage. In my opinion, you could be putting that MP to good use; specifically, instead of topping off the tank every five seconds, you could be doing some damage.

That being said, if you're not comfortable stance dancing, don't DPS as much! It really depends on your play style. Nonetheless, I think every healer should consider at least some DPSing during those instances when everyone's not taking too much damage.