Of course they do not need it, but what if the desire is there?
If one did not want to be bothered by human interaction then they would slither off into the opposite direction. I have a couple that do just that. Surprisingly enough however, one of my most stubborn feeders as of late was taken to the herp society meeting last night for a presentation. She was handled quite a bit, passed around from person to person because they had never seen a Savu python in person before. And what do you know, she STILL ate later that evening.
We have snakes that lift their bodies and climb up without even wanting them to, LOL. Morti will go to straighten the pvc perches in MacBeth's (the male Moluccan) enclosure and he will come straight out to Morti instead of going sideways and behind the enclosure and tv.
Need? Certainly not. Want? Could be, it seems (I said SEEMS!!) that many enjoy it. As soon as they discontinue to view a human as a threat, one would imagine that they 'enjoy' the exercise we offer them.
I would also like to add the behaviour of some snakes around certain people. The previous keeper of MacBeth swore up and down about the vileness of the animal. How he had bit him in the face several times. Morti has had MacBeth for over a year now and has not been bitten once. What does that say? That Morti is a better handler? Well, yes, I think he is, but then I'm partial, hehe. But I do think that some snakes have preferences, like birds do, for certain people. Why does my Irian Jaya always strain to get back to me if someone else is holding her? Many behaviour characteristics are present but not quite explainable because of their inability to communicate on a level we can understand, or vice versa.