Linux requires that you use the command line anyways. For example, you can't even format a USB disk unless you spend an hour looking up an obscure command.
Ed: from your other comment in this thread, I think you haven't. I don't think anyone has ever been required to use the command line to install things in Ubuntu (that are in the package manager which contains most things most users care about), but my memory only goes back to Dapper.
I have several non-geek friends who use linux, and they almost never need my help. They don't know the first thing about the command line.