Even though the spinning sprockets look neat, I can attest to the fact that if you run bare with no front cover long enough the sprockets will gradually erode their sharp corners that retain belt teeth. The dust and dirt do it, like throwing sand in the belt path. Cam belts and sprockets don't like that. And when I did it I was always thinking, what if some day going say on gravel drive and you spit up a small amount of rock into the crank pulley? You could easily be walking home in a few seconds. I had impact cuts inside my belt after removing it after no cover running for a while. The sprockets had to be replaced, they SHOULD last forever with a cover over them. Then there's always the crank snout seal, they don't live half as long when exposed to lots of dirt.
I ran with no cover for a solid two years or so, but not wise. The belt erodes quite a bit more. Of course, the flip-flop is that I could change a belt with no cover like that in maybe five minutes, LOL.