@Seirdy I can't answer for @theruran , but what would lead me to create one:
I have a habit of extracting forms into their own webpages, which brings with it the question "is there a better way of structuring our markup to declare forms the way I'm handling them?". And if I ever get to creating a WYSIWYG CSS editor I'd want to answer that question so I can use it to declaratively define the organization for all the controls altering the CSS properties.