No such thing as cage aggression? What about the countless videos we have seen BHB put up where they get bit sticking their hands in the tubs and such? What about retic keepers like myself who have to hook-train their snakes so they will not mistake us for food when we stick our hands in the cages? Snakes can certainly be cage aggressive, and not every snake will behave the same way.
Onto the OPs original question, I personally do not move snakes out of their enclosures to feed, and because I hook train my animals, I do not have to worry about them associating my hand with food. Instead, they associate me touching them with the end of the hook with getting picked up and taken out of the cage. This is mainly just a technique that big snake keepers use, but I do know that some ball python keepers do it as well.