Have an intercom for music/nav - I think without it I'd have gone postal on the daily commute to Oxford. Autocom threw in a Bluetooth unit for my phone as a freebie. In the 6 years I've had it, I don't recall ever using it.
Unapologetically I have my phone plugged in via cabled headphones for satnav and camera warnings (in case I forget). Having lost another friend this year to SMIDSY, looking at a map or screen is valuable time distracted from road obs. I don't listen to music though, the Pani's soundtrack is way better.
I don't ride the same roads day in/day out, so I prefer an audible alert rather than looking out for what's hidden behind a sign 8 foot up. If I'm doing a ride out on a familiar road then of course I don't bother with any of that gps/mobile crap. Each to their own.
Driving a car is a chore, I need the distractions. Riding the bike a whole different ball game, for entirely different reasons. I want to enjoy the whole experience of each ride, why the hell would anyone want to dilute the experience with music or phone calls..?