If I had to guess, I'd say the people who read 37 signals' blog (and HN) are much more likely to over engineer than under engineer. Most of the client work (and I've done my fair share of consulting) I've seen suffers from exactly what you describe, but those aren't the people who are going to read 37s' blog.

However, I've also worked on the opposite end of the spectrum, lots of turbo nerds who were big on planning for every eventuality (and WERE the types to read 37s etc) and that suffered heavily from exactly what he describes here.

Know your audience!