I also used to feed live when I got my first corn snake, king, and ball.
My reasoning behind it was, "It's what they'd have in the wild and I want to keep them as naturally as possible!"
Eventually though, I couldn't stand hearing the mice screaming, I got bitten really bad by a mouse, and I came to the realization that there is nothing natural about holding a live mouse over a snake's face, or keeping a snake in a cage. Now, I know many people, including myself at one time, used to logic of them eating live in the wild to justify feeding live in captivity- but one must remember that there is nothing natural about keeping a snake in a box. Even a well decorated viv is still a box. Frozen thawed is also a whole lot cheaper, and I always have mice on hand, I don't have to worry about a snow storm, or car trouble, or work on feeding days. Plus, my snakes are at no risk to being bitten by a rodent. I also have a ball python and boa, and I don't want to have to buy a live rat or rabbit every two weeks, and the amount of damage that those animals could inflict are just not worth the risk. I'd like to add that my snakes eat f/t just fine and still constrict their food, it's no different than feeding live, but a heck of a lot safer for everyone involved and cheaper. I would like to add that I've never had an issue switching any snake to f/t from live before either.