funny this thread has come up, I've installed UV filters and kept lens hoods attached to my lens religiously for 10 years often wondering why exactly but I don't make money from my photography so have always felt slightly more cautious about my equipment.
Last month I bought a 24-70 Mk II which was a huge sweat enducing sum of money for me and the UV filter was quite expensive and I ummmed and ahhhed but went with it anyway. I was on holiday and hadn't got round to insuring the lens but went out with my new lens anyway as I have never damaged a lens before in my life.
The next morning I was walking along the street and the lens hood fell off and shattered on the floor, oh well its just plastic, but then literally 15 minutes later in the hotel hobby I dropped something on the floor and crouched down in a twisting motion with enough momentum to send my heavy camera, lens first swinging into the corner of a marble desk. Crunch.
Heart stopping moment for sure but by a miracle the impact on the UV filter was enough to stop the momentum of the swing and the actual lens was completely unscathed. The UV filter cracked and I had to replace it with another £70 filter but rather that than £1500!