Good Wikipedia page on the history and status of the desktop metaphor. Highlights:
The desktop metaphor itself has been extended and stretched with various implementations, since access to features and usability of the computer are usually more important than maintaining the ‘purity’ of the metaphor.
Hence we find trash cans on the desktop, as well as disks and network volumes (which can be thought of as filing cabinets — not something normally found on a desktop). Other features such as menu bars, task bars, or docks have no counterpart on a real-world desktop.
In recent times the filing cabinet and desktop metaphor has become less important, especially since the advent of very large storage media, which can make the easy navigation of large numbers of files and folders problematic.
The Desktop Metaphor was first introduced by Alan Kay at Xerox PARC in 1970 and elaborated in a series of innovative software applications developed by PARC scientists throughout the ensuing decade.
Some schools of thought on interface design regard the paper paradigm as detrimental to productivity, taxing on the user's cognitive conscience, and responsible for a slow learning curve for novice users.
I can't help but think of the example of the horseless carriage:
It's no secret that when new technologies and innovations come along, we tend to look at them through the prism of what we already have. We look at them as a minor improvement on what was done before -- this technology lets us do something faster or better -- rather than at ways that it enables us to do something totally new. Because of that, you often get amusing attempts at reinventing the old with the new that don't seem to take any advantage of what the new innovation really allows. Source
