Touch / smell / taste / etc... These are all senses... If your only pleasuring one sense (imagine plugging your nose and eating a meal which you couldn't taste anything) - you wouldn't have nearly as much satisfaction/pleasure as if you had the other senses stimulated as well.. Which is why a meal has an aroma, a taste, even a texture..
Imagine having a tongue as large as your whole vagina, being able to fill you completely. Doing 'tricks' and more. As every piece of your sex organ is being stimulated, imagine a slight suckling sensation. Sounds perfect right?
...Now imagine being able to see all of this versus seeing your hair. ;P