Overboard with the rules of magic

So there have been several people who have reviewed my script and they pointed out some things that need to get changed. One of the things that everyone points out that needs to get fixed is in regards to the rules of magic. I had written in at one point that the elven and fairy races cannot channel the natural energies like humans can. I came up with this after reading the stipulation in a series of fantasy books called The Dancing Gods series. It was a nice little rule that played in with Areil's mixed heritage, and also creates a reason for why there are so few mages left, because most of the magical beings would have some kind of fairy blood in them. However overall it just doesn't seem to work and needs to get nixed. That has been the sentiment of several of my reviewers and I agree.