The quick answer is (feel free to disagree!), this is a great way to style a blog or microsite, but quickly gets out of hand. Using presentational classes bloats your markup but the size of your CSS assets will remain relatively constant, while using semantic class names requires writing new CSS for each new piece of content. The return you get on sacrificing some legibility in your markup increases with the size of your site. Large applications (or multiple applications that share the same CSS codebase) can also quickly run into the 4095 selector limit in (older versions of?) internet explorer. Using presentational classes has the added benefit of not requiring back end developers to write CSS (nobody likes writing CSS). It's mostly a matter of taste, but I can tell you from personal experience that CSS bloat in a large web application is easy to avoid and a nightmare to fix.