I think it boils down to what experience a person had before and what they need to do. Anyone who played 3d games has better chances to have spatial and visual investigatory abilities (and benefit from it), and anyone who worked in business knows that your files have to be sorted and hierarchy’ed. When needs do not meet experience, they want a single always-on-screen button to start the part of a system they’re familiar with.
As a side note, this caused me to throw Ubuntu on a desktop/laptop for a few of the people who needed the most support, and within a month they didn't need any help and were trying to get me to install it on their friend's machines.
Seriously, I was constantly being asked by old ladies to start an underground Ubuntu support network. They just needed a way to browse the web, upload photos to facebook, and play farmville. That was it, that's all they wanted to use it for.
If I were to do it again today I'd use ChromeOS probably.