I think another point to consider (applicable to any development, really) is the trend line. Which is more likely, a simple thing become too simple or a complex thing becomes too complex? You have 0 CSS rules. Are you going to wake up tomorrow to discover you have -10 rules? You have 7000 CSS rules. Are you going to wake up with 8000? (70000?)
So no secret I prefer simple, but I think a less contentious assertion is that visible problems are better to have than invisible problems. Elements without styles are easier to spot than styles without elements. The latter is obviously a lesser problem in the grand scheme of things, at least to start, but also more likely to grow unchecked into a major problem.