It would be kind of like having the general public seeing me walk down the street wearing my ceremonial robes (for those who don't know it, I'm a witch) and burning incense and chanting invocations to the Goddess. It's something that could be just as easily done at home without drawing attention.
It's also kind of like having Jehovah's Witnesses knock on your door and attempt to spread their 'good news' in a place/to a person who neither needs, wants, or welcomes that particular worldview. If you're doing D/s activities in a place with children or otherwise 'innocent' persons, you're kind of forcing them to witness your worldview, flaunting your different view before them. And if you are doing that, then they aren't going to like you any more than they like those door-to-door preachers, and instead of fostering understanding and tolerance for your way of life, you're just irritating others and confirming their belief that these sorts of things shouldn't be okay. activity between consenting adults should be carried out between/among consenting adults, and not where anyone can see them.
(My apologies to any Jehovah's Witnesses out there. I meant simply to use an example, and you happened to be the ones I thought of, since I received a visit from two Jehovah's Witnesses last week. They were extremely persistent about my taking one of their bibles and pamphlets and talking to them later again. Even though I made it clear I wasn't interested.)