Personally for me, it's about the control I have over my recipe. There is absolutely nothing wrong with Kits, and as many have said, many retailers sell quality ones. I personally like the feeling of picking my own hops, talking with this forum and homebrew shop what hops go well, what grains are good for the recipe, and then building that recipe in Beersmith. Then, if the first version of the recipe is meh, I can always tweak and adjust things.