Considering how central the URL is to the World Wide Web, it should really be blatantly obvious that it needs proper attention during the design process of any new website. It's not always easy, and I for one have certainly at times been guilty of poor URL design, but making changes later can be a tall mountain to climb.
URL Design is a complex subject. I can’t say there are any "right" solutions — it’s much like the rest of design. There's good URL design, there’s bad URL design, and there’s everything in between — it’s subjective.
What I especially liked in the article is the notion that URLs are for humans. SEO is useful, not the least because it employs a whole industry, but really the human you're trying to attract to your website should always be at the centre. But all other things aside, the absolute most important attribute about a URL, is and always has been is that it works, and that it keeps on working.
What makes a cool URI?
A cool URI is one which does not change.
What sorts of URI change?
URIs don't change: people change them.
Having revisited older posts in this blog, it's unfortunate to see so many dead external links. Luckily there are projects like the Internet Archive that make internet archaeology possible.
So do the internet a favour: keep your URLs alive, and donate to the Internet Archive project to mitigate the consequences of dying URLs.