For me it's not about talking on a phone while riding. It's about not missing a call because i'm on my bike travelling between A and B and someone at A or B needs to get in touch with me. Right now, it's "crap, my phone's ringing"... Signal, brake, find gap, pull over, rip off gloves, rip off helmet, open trunk, find phone, crap I dropped it, grab phone... "1 missed call". It's not always important that I be available by phone, but there are times when I know someone will be calling yet I still have to get from A to B during that time period.
In my car, I have a bluetooth headset, and I do wear it while driving in case I get a call. On the highway, I'll put myself in the left lane and stick with the traffic in front of me. There's nothing else I need to worry about, so it's pretty mindless driving anyway... All I have to do is not rear-end the guy in front of me. In town, i'll pull over. "hello?" "hi, it's ....." "just a sec while I pull over..."
Being able to connect to an FRS for rider-passenger and/or rider-rider communications would just be a huge bonus.