I despise frameworks like this. They cater to a crowd that I don't believe exists. Who goes and wants to just toss together a mobile-friendly site but doesn't have the skill set to do it without a framework like this? The huge companies that do this rather write their own and the little guys generally have hackers who can write something more efficient. The simplicity of HTML and CSS make frameworks for it seem rather silly.

Edit: That is, of course, unless it's something like YAML or SASS or LESS which completely redefine how to write the code.