You sugar coat it far too much, and the "advantages" you list and claim are utterly unfounded nonsense.
When you basically have classes for every last joe-blasted CSS property, how the hell is repeating those classes over and over again in the markup "writing less code"? It's MORE code than you'd write if you just used CSS properly; that you're not writing the CSS as CSS doesn't change that!
Instead, you're pissing all over the markup with presentational classes, undoing all of the progress HTML 4 Strict and CSS brought to the table. It is the bleeding edge of 1997 coding mentality and methodology, which is what makes it and every other front end HTML/CSS framework so mind-numbingly DUMBASS!
The people who claim these derpy moronic garbage "frameworks" don't know enough HTML or CSS to code a single damned line of either, and have drunk far too deeply of the tainted flavor-aid.
See my own article on the topic: