Why do some people choose to use pre-emergent herbicide (besides ecological reasons) and think it not worth it?

the benefit of a preemergent is that it prevents those weeds from germinating, so you don't have to battle them as full blown plants. The downside, I've found, is that there is a narrow window in which they will prove effective. I don't know percentages, but do know that most users are those whose main interest is a lawn. Our concern is in actual garden beds, both raised beds with cutting flowers, and landscaped beds of ornamentals and perennials. It just saves us a lot of weeding come spring.