Can anyone explain the need to "come out of the closet" as many put it?

I see so many posts across the internet, from facebook, reddit, all the way to little unknown forums and fetish groups.. all about "coming out" to friends and family..how proud they are... their struggles... ect... And i just don't get it...Maybe it's because i have no family and just don't care... But i don't see the point of "coming out"... The way i view things is that you are who you are... Those who you are friends with, close too, and whom accept you.. are what matters.. "coming out" to my family never meant anything to me and honestly i never really did "come out".. It wasn't some big milestone when my mother found out about me.. In reality i couldn't care =/So am i missing something here? Why do people put such importance on "coming out" instead of just "being themselves and being accepted by whomever"?