You're right, of course, but it's very limited in scope.
I actually hadn't thought of it, but now that you mention it, I still don't think it matters in terms of noise prevention.
Most vehicles are bought (I think/guess/believe) without giving a second thought (iaw shit) about the noise they cause.
They're bought because of price / space / availability / whatever. If that behaviour stays the same and cars overall get more quiet, there will be less noise. That's cool with me.
People who buy Harleys will continue to do so. Those machines are bought, as you wrote, because of their image (getting bitches all wet). They are cool, great, fantastic and they will get bought. AFAIK, Porsche invested quite some money to *keep* the sound of the 911 the way it was when they switched from air cooling (VW Beetle! proud former owner of a 1302 speaking) to water cooling (which is far more efficient) in the second half of the nineties.
If the majority of cars will be less noisy, I shall be pleased.