As a gay Brentford supporter (a GayBee, if you will), might I offer a perspective on this...
With regard to coming out to friends/family/colleagues, I'd suggest that's something every gay person is better off for doing. Not because it "matters", but because it is an aspect of who the person is, and to be open and honest about yourself and to feel safe and loved around people in your life is massively important.
Personally speaking, I would not be happy or secure in my life had I not come out at a young age - indeed the 2 or 3 teenage years before I came out were pretty horrendous psychologically. Not because of homophobia, but because fear of the unknown i.e. what would happen if I came out? As it happened, nothing. In fact the lack of shock was a bit irritating. However, I was immeasurably happier in my life for doing it.
So, when it comes to a person in the public eye, especially a sports person (and even more especially a footballer), I would assume it's very difficult indeed. Now I don't care if no footballers come out publicly, ever. The problem is that with the intensity of public interest in "famous" peoples lives, I'm not sure how easy it would be for a footballer to come out privately without being outed publicly. If fear of the latter stops a person being able to be open and honest within their private, day-to-day lives then that's a real shame. That sort of closetedness is real and does happen, not jut in football.
As has been suggested on here and other places, it probably does require a current footballer to come out so the football world can show it has grown and can deal with such trifles. I don't personally feel that homophobia would be a big issue in such circumstances, but it's the unknown and therein lies the fear. That barrier will I'm sure soon be broken, and whilst it will be the merest of ripples in social impact, it will make individuals lives that little bit more comfortable.
Hmmm... I always hoped my first proper post on here would be funnier. And less gay.