The lens coatings on most modern lenses are very good and provide quite a bit of protection against bumps and/or flare. Knock on wood, I've never really had an issue with worrying about protecting a lens surface. I take the lens cap off before I start shooting and put it back on at the end of the day. In the meanwhile, the lens front element is always exposed to the elements as my camera is slung from a shoulder or at my hip. My philosophy is that if I'm going to buy a lens, I'm going to use it. Why else would I buy it? (I'll add that I've used quite a number of Canon, Nikon, Leica, Zeiss and other lenses over the years.)