A designer worth their pencil might need longer than worth 50$ to get to an initial mix of good look.

If it's somehow wysiwyg it might also speed up things a bit.

True, but you're going to need that designer to work on that initial mix whether it's with this software or something they're much more experienced with (probably Adobe CS) - unless the UI for this is radically better than the mockup tools that pro designers use, the marginal utility of outputting LESS variables probably won't add value, and might make things more complicated by introducing an additional tool into the pipeline.

I have different use cases in mind:

- A designer that don't know/don't want to write css. She can keep her design process and use Strapfork to create the css components.

- A designer that likes the workflow that Strapfork proposes (UI is part of the brand -> design components | design UI with mockups. Mix both in directly inHTML and have the final design in the browser, no need of photoshop).

- A backender that just want to customise bootstrap easy and fast.

This is great for MVPs where you can't afford a designer.