We still have societies, communities and even families that are very closed minded and prejudicial...that's what makes it a big deal. There's still the sentiment that men and women are supposed to marry and have children... and if you don't then there's "something wrong with you"...and it goes beyond even sexual preference. If a woman or guy chooses not to marry, then they are asked "when are you going to get married" or else there's the immediate conclusion that she's lesbian or he's gay. I know from my own experience (before my wife fell pregnant) that so often we'd be asked why we don't have any children...as if by not having any, we are doing something wrong.
We live in a world ruled by stigmas, labels and generalisations. Everyone and everything needs to be classified and put in a specific box. People aren't seen as the individuals that they are, they filtered through a list of rules and expectations. It's these attitudes and approaches that makes coming out such a big deal...most especially for the person that is coming out, because not only does that person have to deal with the reaction, perception and prejudices of those around them, but they first have to deal with their own...bear in mind that we have the ideals of our societies and families brainwashed into us...that person has to first accept that yes, he or she is different from what is dictated to be the "norm" and yet it doesn't make them any less of a person.
You didn't need to tell your parents that you were straight and you didn't have to deal with inner conflict because you have fallen within that "norm". To some extent you have taken your experience of falling into that "norm" and used it to filter the lives and plight of others with...which really isn't fair. It would be like me as a white post Apartheid South African saying, "what's the big deal about being black? We're all equal" What seems to be forgotten is the years of struggle and fighting in order to be seen as equal. To receive equal rights, values and respect.
You are viewing all of this through your own world and expecting others to conform to your ideals, it sadly doesn't always work like that. If you'd really like to understand why "coming out" is such a big deal, I suggest that you picture yourself as being gay and paint a fairly bleak picture - homophobic family, homophobic friends, very conservative closed minded environment...put yourself in the shoes of another, but leave your pre conceived ideas or beliefs (which is wonderful, it's great that you see nothing wrong with homosexuality) out of the situation (the whole world isn't made out of HappyHammers - pity
) ) and I think that you will then find that your question has been answered.
A very good thread by the way. Thank you for starting it.