I think Tim Cook is doing a very good thing by publicly coming out, because I think it will show those who are afraid exactly what kind of reactions people will have. I think overall Tim Cook was supported when he came out, and hopefully that will show others that they will be supported as well.
The importance of a person's sexual orientation is becoming less of a factor, and thus less interesting, to the world as each day goes by. It is important for all of us, regardless of our sexual orientation, to see gay people as equal, and it can only help to have the head of one of the most well-known corporations in the world as out.
Whenever a person takes the step towards the betterment of themselves or society, they provide encouragement to others who would like to do the same. It enforces the idea that people just like ourselves are able to do it. Most people find inspiration in such actions, so it would likely give them hope.
Tim Cook coming out is a major step towards helping gay youth come to terms with their futures. One of the big issues for gay youth is the lack of any role models to aspire to, so many jobs seem to be out of reach for a gay person because of discrimination. Seeing an openly gay person in one of the most powerful positions in the business world will inspire them massively.
Why would publicly announcing a sexual fetish be helpful? CBS News ran a list of sexual fetishes including Agalmatophilia (people with a sexual attraction to mannequins), Ursusagalmatophilia (sexual attraction by dressing up like an animal), Paraphilic Infantilism (wearing a diaper and pretending to be an infant), Autoandrophilia (women dressing up and pretending to be men, and many others unfortunately. Depravity is apparently a bottomless pit and it doesn't give me hope.