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.
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.
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.
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.