The Peter de Amato cutting's were relatively expensive (over 100) but I may get one yet!
Joe, Nep Gracilis, and Griff, are right on. The way I understand it from my own experience, the leaves are for collecting light for photosynthesis. The more light you have, the less leaf you need to get the necessary amount of photosynthesis. You can try this by moving one of your plants very close to your light source. You will get the same effect...at least with hamata.
I dont suggest doing that with all neps though, as some don't appreciate high light levels, and may stop growing all together.