Tongues give an additional layer of sensation to a dick when used correctly. After all, blowjobs aren't just about putting a dick in your mouth, it's about stimulating a man's dick in more ways than one given what the human mouth can do to it.
The tongue itself can caress a man's dick that's nothing like what fingers can do. A man's teeth can lightly grind on the surface of that dick, giving a tingling sensation that any other part of the human body can't.
