I agree, its not needed. It acts as an anchoring aid to help ensure you anchor at the same spot each time. I use them just becouse I dont feel very comfortable with out one. As straightarrow said, they will become a problem sooner or later, with low light being the biggest for me.

If you do want to use a peep, and are concerned about low light problems, try a C-peep, Ive been using one for about a year now and really like it, In my opinion, its the best out there for low light. And, I just discovered that if you use a string loop, you can ditch the rubber tubing also.