Why is hot-rodding such a big industry? Why was hardley ableson so big? It's probably not because (the people who drive them) don't like how the engines of those vehicles sound. I'm going to take a wild guess here and say that they like how those engines sound, and don't care if they're too loud. Another thing is that their ears have probably adjusted (become damaged) to the point where they're comfortable with the sound. Sometimes the exhaust reverberates, and it never sounds good.
Apart from that, loud pipes don't save lives, motorcycles are inherently less noticeable to the average driver, so the probability of an accident is already so high that the exhaust system makes little difference statistically. Also, this isn't helped by the fact that many who preach this mentality are the same ones who don't wear a helmet. Another thing, please don't confuse the people with fart cans and speed holes in their mufflers with those that actually have good exhaust systems that sound good but aren't too loud.
Having said all that, human drivers are inherently flawed, and excluding motorcycles, I certainly wouldn't mind it if there was nothing but driver less electric cars. If they could work out all the kinks, there would be less accidents, and I could make longer trips without having to stay at a motel.