Interesting to see all the followups. I had no idea that anyone cared about this. Reminds me of guys who don't like people touching their cars. I'd encourage all the folks advising the OP to be curt or to ostentatiously rub out the smudge to imagine a guy in a polo shirt wearing Ray-Bans. Perhaps his collar is turned up. Now imagine this man behaving the same way after someone touches the finish on his Corvette. You are the geek equivalent of that guy.

Except Mr. Polo doesn't have to spend ten hours a day staring straight into his car's finish.

I find them annoying too, but the safety advantage while riding on highways is clear. The safety of the rider is, in my opinion, of more importance than any mild annoyance a loud bike might cause. That said, I suspect, like you, that safety was not the reason a lot of riders picked a loud bike.

I've always liked the "brain is to self as guitar is to music" analogy. Sensory input is the guitar player. The monkey represents sharing.