I think you've hit the nail on the head here - there's an enormous amount of pure visual-design influence in UIs these days, prioritizing aesthetics over usability. We can see it in this proposed Wikipedia redesign, in Microsoft's Windows UI overhauls, and in plenty of other websites.

There are major problems with what we see in the 'Athena' screenshots. Why are the navigational controls at the top of the page - ones that expose functionality applicable to the entire site, not the current article - skinned with a photograph taken from the current article? What does a picture of the Beatles convey regarding how to find information on Wikipedia?

The author says that the Athena skin "emphasizes content", but it causes article content to bleed through somewhat into the functional UI, compromising both. This isn't a good thing.