It's hard to break pills in half evenly even when they have a groove for that, and I've had some cases where I want to take half of a pill while the pill is tiny and hard and doesn't have a groove. Doing that with a kitchen knife is extremely annoying and potentially traumatic.
(That said, uh, I don't use a fancy 30$ metallic pill cutter, but a cheap plastic one with a V-shaped slot that holds the pill in place.)
(That said, uh, I don't use a fancy 30$ metallic pill cutter, but a cheap plastic one with a V-shaped slot that holds the pill in place.)