Public self exposure of their sexual practices is part of the gratification of the fetish.
The erotic is exotic theory. They LIKE (and need) being public perverts.
My pet theory is that the public flaunting of homosexuality is part of distracting others, but most importantly the individual, from that person's inner self-hatred. It's a ruse. No one who truly loves himself needs to hold outlandish parades with hundreds of other like-minded individuals.
Of course, this theory relies upon my personal belief that to deny the natural order of life, in this case that one man marries one woman and the two live monogamously for the rest of their lives, inherently produces unhappiness. My only support is the amazingly high levels of depression and other mental illnesses among homosexuals. While the liberals want to think this is due to society's persecution of gays, I tend to believe it is a result of the conflicted conscience over such spiritual poverty.
I could be wrong about this, but I believe the theory holds more truth than not.