I think it's more to make the food not look scary to kids.
Then adults who experienced that, or want to experience it, start doing it too.
However, your logic is flawed, since Yo-chan is exceptionally cute!
\(^o^)/
Let me be clear here. BenBen licks my toes every Wednesday as a form of gratitude for reading and reviewing his story. There is no correlation between my cuteness and licking anywhere else on the body at non-specified times. Pure and innocent toes. Don't make things weird.