I think about it like this.. snakes do come to recognize certain people. They become familier and relaxed with handling. We know they can see. We know they are shy and can be defensive. I believe if a glove is used to pick up a snake, you cant feel the exact amount of pressure you are using. If its a glove which is thick enough to block any teeth. A glove feels different to the snake than a bare hand as well. It looks different. it smells different etc..

For removing water bowls one can always use a small piece of cardboard, a hide, a towel, to block the snakes face and distract it. Just touching it with something will generally bring it out of feeding/defensive mode.

If the owner is nervous enough to want to use a glove, it should not be a permanant thing. It should also not be needed once the snake is lifted from the enclosure. I dont think its necessary when there are other, less stressful things that can be done but to each his own. These animals have a very calming affect. The faster an owner gains confidence and learns ways to calm the snake without causing stress, the faster they can interact with the snake and see how wonderful they really are.