Could people who don't understand why some other people object to the choice, read what SteamingNit wrote earlier:
For as long as some women insist on being addressed in a way which takes into account the fact that they've got married, the 'choice' of Ms cannot work as it was intended to ('I am a woman, as opposed to a Mr'), because all it can mean is 'I am a woman who won't tell you whether I'm married or not' - so we're STILL defined by marriage, because your choice is
Married Woman
Unmarried Woman
Woman who won't say whether she's married.