If you think about it, organs that serve dual purpose for excretion and sex is disgusting. You're doing oral where pee also comes out. Most people don't think this is terrible because speciesm. We think possessing anus hanging over one's face is disgusting. But if snails could talk, they would say it is disgusting to have sex where your organs also just peed.
i guess because the urethra is prone to urinary tract infections so it's kept away from the bacteria-expunger and put with the Goal Of All Evolution device