If "loud pipes save lives" then why can't the car drivers have straight pipes or run open exhaust cutouts on the street? My grey T-bird apparrently seems to go invisible ALL THE TIME and I want some of that extra safety too!
Is it the same reason they don't have to even wear a helmet, yet we're legally forced to wear seatbelts inside a many-thousand pound steel cage built to protect us? I know that we need organ donors, but come on.
The excessive throttle blips while pulling up to a stop *could be* rev matching for the downshifts (they're not, all the bikes I've ever watched do this hold the clutch until they have it back in neutral after stopped)
It *could be* trying to keep a badly adjusted carb from loading up on fuel from idling too long (it's not, all cruiser bike carbs aren't bad and if yours is, there are even people you can give money to who can fix them!)
Just like you don't have to keep the throttle pinned until your clutch is fully disengaged for a gear change, but it's not as loud that way and the revs can match faster. Or you don't have to rack them off going under every bridge, honest the trolls won't get you if you don't.
+1 on the monkey / loud noise reference. There is a weird primal feeling of power to drive or use something obscenely loud. Doesn't really seem to matter if it's a car, chainsaw, motorcycle, subwoofer, rivetgun, air tools... It wakes up the unevolved primate part of your mind. "Hahaha, I can shatter the peaceful silence with my really f**king loud thing! Bow before me all things that are not loud!!! I am loud, destructor of worlds!"
So, wait how do the guys with Electric Motorcycles ride safely? I mean, they're QUIET, that can't be safe! Put a card in the spokes? Get a megaphone and pretend they're Crazy Frog?
Brrrrrrriiiiing dingdingdadadingding baba breeeeeeeeee breeeeeeeeeeeeee breeeeeebaba ding bada biiimm biiiiiiiimmm...
In conclusion: Loud Pipes piss everyone off.
Loud pipes make people build quieter vehicle cabins and put in bigger stereo systems so they WON'T HEAR things like bikers or your child / pedestrians before they run them down.
Pinkie wave at bikers.