I used to think the same thing, but then I met my husband who rides, and now I do too. The way he explained it to me is that you need people to hear you, they may not always see you, you at least get a second chance to not get ran over if they can hear you.
There are few things I hate more than unnecessarily loud bikes. I could care less what the justification might be. Most people hate this shit, and nobody is impressed.
The Little Dick Boogie, Nobody Loves Me Anymore and I'll Fuck My Bike Before I'd Fuck You (But Thats Only Because I'm Sexually Attracted To My Motorbike And Not To You)
I remember a comedy sketch. A guy is walking down the street when a uniformed captain interrupts him angrily and asks why he's not at work. The captain drags him to the docks and puts him to work. Turns out the guy is wearing a shirt with a generic print like 'Navy Club Est. 1972' - Does anyone remember where this is from?