> When was the last time someone did a major CSS overhaul without changing HTML
True perhaps, but that's because lots of people write poor-quality HTML. By following best practices like this, it becomes much less necessary to overhaul your HTML during a design change.
If only that were the case. HTML and CSS are super tightly connected. Want to change a float? You probably need to reorder your HTML Want to change some margins? Time to re-nest some elements.
Even the finest HTML in the world often needs to be modified when the CSS changes. It's a shame but them's the tools we have.
We just completely redid the design of our site and barely touched the HTML other than the top nav, and that's mostly because the content changed there, and the changes were mostly deletions.
In my experience a lot of developers solve problems using HTML that could be better solved with CSS and a sprinkling of Javascript, because they don't know the DOM or CSS well enough. I think that's what most often leads to the situation you described.
In any case, for someone developing with a framework, they're already mucking about with templates, in which editing the classes is trivial to alter.