As a programmer, this is awesome because I can spend the rest of my time on the interesting programming stuff. Really, it appeals to:
1.) My complete lack of understanding of the intricacies of CSS and web page design.
2.) My mindset as an industrious but lazy programmer.
3.) It can be made to be generally portable.
I can see that down the line I might want to replace it with something else or hire a real designer to make me real buttons and web page styles, but it an excellent tool for the rough drafts of different ideas that I have. I can put things 'here' and 'there' on a web page quite easily, and that is really what I want/need.
It is much like a writer throwing down his ideas stream of consciousness style onto a piece of paper. He knows that he will have to edit eventually to make it consumable, but for now, he just needs to get the ideas down on paper while he has them.