The standard must be easily implemented. To get a standard accepted, ease of implementation needs to be designed in, that is, complicated, hard to use standards are in some sense invalid. I see some standards that are verging on the Baroque. CSS is way ahead of anything anyone is implementing right now and the features are being piled on for CSS3. Obese standards are invalid.
Ease is desirable because it allows people to get things done.
I worry about XML, when I see 'added extras' like metadata, namespaces, XSL, CSS, XLink crawling out of the woodwork. Not that the goal of these standards isn't desirable. But they serve to make XML complicated and difficult to implement.