I don't have a strong opinion on whether browsers should provide default styling, as it's trivial to override (although many web pages do rely on it). I agree that HTML tag names don't serve a very useful styling purpose, but they provide a useful structural purpose that cannot be easily replaced by using open-ended tag names or classnames. Custom Elements (http://w3c.github.io/webcomponents/spec/custom/) are in the process of being implemented, but I don't think that's an argument for throwing out the standard, structural elements that provide a common API for interpreting document structure.