Personally, I don't feel there is any need to tell others about your sex life or any other part of your personal life with a partner. I wouldn't tell people about intimate parts of my relationship, BDSM related or not.
However, that's just me in a way.
There are some people who are more sharing or who feel the need to tell people about their lifestyle; and I think it's amazing that they can be so open about themselves.
It's just one of the those things, and I think a lot of it does depend on character, and how open you are to others; it's not a bad thing either way, and it's just a shame that by telling others you're in such a vulnerable state and often so open to insults and aggression.
I think that's the main reason I wouldn't spread around what I was 'into', because a lot of people don't understand anything about it and just assume there's something wrong with you - it's a lot like how things used to be for homosexuals. There's a lack of education about it that's positive or truly accurate, and it makes talking about it often quite dangerous.