On my shorter lens last year I had to replace the UV because of some scratches/marks caused from dirt/mud from the bikes. It was on a 17-70 lens so was reasonably close (I have full access to any part of the track and was sometimes only 2-3 metre's from the bikes), and was trying to get some shots from behind the bikes as they left the corners spraying dirt, I also had the lens hood on. I'm not saying they will stop all damage but in some cases they can be handy to have.