Not just sexuality, in general:
Because people love perversions, fornicating and immorality in general.
What is good and normal isn't attractive.
Try to live simple, normal life, try not to drink, not to watch porns, not to be fornicator, do not do drugs or smoke, don't eat junk food, dress decently ect. most people will look at you like you're crazy and they will make fun of you, mock...
We live in a world where what is not normal is promoted as normal. Simple.