I can think of only handful of scenarios that would require anyone to have their phone's "ringer" on in a public place. Mine is on vibrate unless it's at home with me and thus it doesn't annoy people around me. I'm not a big fan of unnecessary noise - especially of the inane variety - so ringtones tend to really get on my nerves. I've only said something to someone once, though, and that was a co-worker who constantly left her phone on then went to three-hour meetings, leaving us to hear it ring and ring and ring. Loudly. We finally wrapped the stupid thing in her sweater and stuffed it in her desk drawer, then had a talk with her.
I've never understood the need to have unique ringtones for certain people, either. Surely the person's number and contact information show up on the phone when they call. So why the need for a special ringtone? That's always confused me.