I have thought about this before and I have to agree with you from about the same angle.

Everytime I have seen it public (outside a forum such as the Flea) it's struck me as something a bit too intimate to be in public. It just felt like it was opening a door of TMI. I don't have a problem seeing someone in a collar but seeing them be lead around by a leash is more information than I want about a strangers sex life.

Maybe I'm being a bit prudish (and I'd really like to see someone try to accuse me of that ;-) but just the way I've felt.