I agree with you. It's silly for people to assume a snake will associate feeding inside the enclosure with your hand and bite you. If you fed once per week, clean once per week, handle once per week and maybe spot clean/water change once per week, that's 3-5 cage opening per week if you practice proper husbandry. And some people think that feeding that ONE time out of 3-5 times will make the snake conditioned to that? Doesn't make sense.
My other point that I always make is the same one you did. If snakes are so easily aggresive from in cage feeding, and associate your hand with food because you feed in cage, then how is a feeding tub any different? LOL. If you use that logic then the snake will learn to associate you picking it up with feeding time! Duh.
So MouseKilla I totally agree with the secon part, and I feed ALL my snakes in cage. Besides, the best time to get bit IMHO is when you remove a snake after eating from those "wonderful" feeding tubs.