I'm not a usability studies person, but I manage a lot of computers and have a lot of users, and watching them work with computers and also listening to them complaining about computers teaches me a lot about how "typical users" work. Most of my users are common people who knew practically nothing about computers but were forced to learn to use them for work.
The most obvious difference I notice about novice computer users and experienced computer users is that novice users love the default Windows XP theme, and they love the standard Vista theme even more, and they loooooove the Windows Aero theme. And they love smooth scrolling and animated windows and event sounds and all the things that I find annoying and slow me down while I'm working at the computer.
This is also true of website designs. You know how web designers always advocate clean and functional web designs, and how to avoid website pitfalls like overuse of animations and bad fonts. But in real life, my users love those flashy websites. And I'm not talking about users who are just browsing websites for fun, but managers and high level decision makers in the company who look at supplier or customers websites daily. So web designers really have to look carefully at their intended markets and design accordingly, and not always design what they themselves think is a good looking website.
When tech people looks at Windows or look at an application and wonder, why did they ever do that? Why did they take out feature x and why did they do a certain thing a certain way? Why are some websites so ugly and have tons of flash animations and yet attract millions of visitors?
Because users love them.