I must admit, I got caught up in buying them for my lenses initially and then stopped as I acquired more lenses. I don't walk around grinding my lens ends into the ground or against the corners of buildings, so don't feel that they need protection from that sort of thing. I also noticed after buying a calibrator for my iMac screen, that there was a nice orangey/brown ring on some of my pictures, thanks to an expensive ($75) UV filter I had on my 50mm f/1.8 lens. I threw them all out, I wasn't going to give this problem to someone else. Turns out that all modern lenses have UV coatings built in anyway. If you are worried about scratching your glass, buy a lens hood, or use the one that came with your lens.