So...?

I had an aunt - well she wasn't really an aunt, just a close elderly female friend, but we called her "Auntie", and I remember her being devastated when she learned that Rock Hudson was gay, and I couldn't understand it.  "He's still Rock Hudson" I remember saying, "same bloke he was yesterday". But clearly to her the news changed things fundamentally.  Why should a person's sexual orientation make such a difference in the way some people see them?  There have been several stories recently about how difficult it was for some men (strangely it doesn't seem to be such a problem for women) to "come out" as gay.  I don't get it - maybe because I don't see it as any of my business.  Indeed I don't see why people feel the need to "come out of the closet".  Why bother? It's nobody's business but theirs.  Am I missing something?