I don't think this movie universally appeals to any particular group - gay men or straight women or astronauts or immigrant farm workers...it appeals on the level of some internal emotional recognition. Folks who don't have the receptors for it just don't, and belonging to any particular cultural, sexual, religious, etc., group doesn't make that happen.
I remember seeing Terms of Endearment, and listening to audience members sobbing at the story, and all I could think was "what a bunch of emotionally manipulative crap this is!" There's no circumstance under which I would have felt differently - I don't have the right receptors to appreciate that filmic experience. And lots of people don't have it for BBM.
The people who think it's slow and boring aren't just being contrary - they really do think that. I can think of many lauded films I feel that way about (you don't even want to hear my list). No friend, no matter how sincerely intentioned, would change that. Even if I understood why they liked it, I still wouldn't feel what they felt.
BBM is a touchstone for me, but I just can't assume being gay or anything else, means you 'get it'. Maybe it's most important to live the message of BBM, instead of convincing others to watch it or arguing about their understanding. And then our friends will get the message of hope and redemption and healing and love and whatever else we felt through us, even if they don't get it from the movie.