The graph of people who will be happy using Linux is a big bi-modal smiley face.

At one end are the people with the computer knowledge you mention.

At the other end are people with very little computer knowledge.

It's all the people in the middle with a little computer knowledge who will struggle when they try to manage files.

But the experts will expert and the uninformed will just use the computer to do the high level tasks they do (e.g. browse and email and store everything on the desktop). Modulo obscure hardware, Ubuntu will just work for them.

Which is not to say this is the year of the Linux desktop.