You're right, "gay" sex is no big woop. It only prompted a flood and an ark and got an entire ancient city wiped off the face of the map. Nothing worrisome there.
You're really comparing apples and oranges here deflecting from the vile nature and evil of sodomy. Ok, why don't we focus on alcoholism? Well, nobody is trying to legalize alcoholism and say it's a beautiful thing we should all partake in! As far as immodesty, I hear my priest making comments about how parishioners should dress in response to some eyebrow-raising, "healthy"-looking twenty-somethings in scant wear. I also hear a lot of people whispering their disgust.
Immodesty leads to promiscuity and sexual sins, and I don't know many Orthodox folks who are ok with promiscuity. Do you? I must be in a weird parish, because practically all the folks I talk with preach abstinence?
The LGBT lobby is throwing their filth in our face 24/7 in film, television, radio, print, online, you name it. We are being brainwashed to accept this nonsense, so I think it's quite obvious why Orthodox Christians should not only want nothing of it, but fight the good fight against a soul-destroying lifestyle that is steadily being digested into our youth as a healthy option for living.