I would have never felt the need to ride with external speakers, until my I took my brother's BMW R1200RT on a trip of several hundred miles to relocate it for him. I have a pair of Sena's that I use and love (they sound great), but it was nice listening that way, especially when parked under a shade tree to eat lunch. The other nice thing is that when I'm on a ride with my brother, he tends to keep the Sena's going all the time, he's pretty talkative. In my case, I can't listen to music, but he still can.
If someone found a nice set of high-power, waterproof speakers and amp that would all fit under the fairing, I'd consider doing it. There is a youtube video of a kid who shows his install on a C14, but I don't like the speakers he's using.