HN has had the same layout and look for a very long time. It works and there has been no need to change it. Keeping up with trends is usually not a good reason to change something that is working perfectly for it's intended use case.
It works very well and is lightweight compared to most websites, but the layout code (nested tables, font tags, etc.) is still pretty inefficient for what it does.
On every device I consume HN from, Mobile (android), Desktop (Chrome and Firefox), from both high bandwidth wifi and as low as 3g mobile, it works to the extent that I literally do not notice load times, render glitches, or any issues at all. If I were maintaining this site I literally could not think of a single reason to change it other than "I'm bored".
