I have a quarter turn throttle lock on my Harley. Using the throttle lock allows me to ride hands free comfortably down to around 30 Mph. I can even change lanes this way. While I don't ride hands free in traffic. I do on the highway. Though certainly not exclusively. Comfort on a bike like mine demands switching your riding style once in awhile. Of course the wind, curvy roads and road condition affect this being comfortable. But I can still ride right or left handed.
All in all I would say it's a 50/50 mix of comfort and bravado.