Earlier quoted context omitted.
the "pop up occasionally" part is what has me stumped - if these tools are any good, they must surely be more efficient than hammering out CSS and HTML (or pre-processor languages) by hand. If they aren't, then why, and if they are, what's holding back adoption? I'm a frontend developer myself and the reason I posted the question is because I couldn't give myself a good answer as to why I wasn't using one myself.
Because front-end development isn’t visual development, it’s interface development. What you’re building can be accessed visually on a variety of screen sizes, through a screen reader, a screen magnifier, a braille display, through print outs and a multitude of other different ways. Conversely in the other direction, you’re also building application interfaces that let back-end systems feed data into the interface, a…
on the backend interfacing side, I suppose that depends on if the UI allowed you to set up fixture data that then flowed into your template tree. I could see that being quite a nice way to visually experiment with structuring your data.