Dry firing is a good thing; it helps muscle memory especially with respect to good trigger management, and it wears down burrs and rough spots in the small action parts. The only thing better is live firing. Do one or the other, or both. Often.
That being said, if you're going to dry fire, do it properly. Yes, the "damage" caused on a properly timed and set up gun is no more than would occur if you were live firing, but the vast majority of people don't have such guns. Therefore, take a very simple and inexpensive step to minimize nipple damage by putting short pieces of aquarium air line tube over the nipples (or a piece of rubber or leather in your Remmy hammer) to cushion the impact. Why tear up the nipples when you don't have to? Even if they are consumable it still costs almost $20/gun and the tubing is maybe a buck! Gee whiz, guys, it's cheap and easy.