Because they are incredibly useful when it comes to certain kinds of food, especially eggs and fish.
I find all the "self-congratulatory" posts on the topic of non-stick pans, and demonization of people that use them, of the "thou doth protest too much" quality. Tons of renowned chefs, like Jacques Pepin, have spoken of the benefits of non-stick. There are ways to get closer to the quality of non-stick with other techniques (e.g. a meticulously cared for and seasoned cast iron pan), but it takes a lot more work and is still finicky.
I totally get it if you don't want to use a non-stick pan because of health or environmental concerns (I find there isn't much to be concerned about if you're not using too high heat on the pan), but this pretending that non-stick pans aren't super useful is silly. I'd challenge anyone to make a perfectly light and golden French omelette with, say, just butter on a non-nonstick pan (it can obviously be done, it's just way harder).