Well when it tightens it's tail around your neck to stop you from pulling it off, and when is could bring most of the skin on your face with it (Remember Aliens?) and your people know that and teach it to everyone in their species, you kinda don't want to choke yourself, and flay your face. Anyway, Ripley didn't have it directly on her face.
Stupidity works in mysterious ways. Its greatest achievement is solar-powered night-vision goggles.