Hey kid, you have no authority or life experience to tell legal adults what they're allowed to do with their dick.
Having to deal with a little feces is just a fact of life that can't be avoided. Maybe some day you will have a baby with your GF/wife and then you'll have to change shitty diapers and there's no complaining about how disgusting that is. Maybe your bitches pussy has even gotten loose from giving birth and you have to resort to the 'back door' to feel anything.
Also, having sex with animals hasn't been illegal in my country since 1971... It's unreasonable to punish people for being too lame to get sex from another human being.