LSLGuy, dasgupta, I refer you both to leenmi’s post and to MacOS X, a secure UNIX that both your [grand]mothers could use.
The average user doesn’t need to have much direct access to his system. He needs to be protected from that kind of direct access, in fact, because he stands a good chance of screwing himself over. This makes UNIX ideal as a real end-user OS, in the most corporate sense of the phrase.
You both mention software installation as a time when he’d need root permissions. Nonsense. UNIX allows you to install your software into your own home directory, binaries, libraries, documentation and all, and run it as if it were system software. Most Linux machines aren’t set up that way by default now, but it would be a trivial task to make the change. Most software doesn’t need direct access to the machine any more than the user does, and UNIX software that doesn’t need it doesn’t demand it. It goes through library functions, instead.
This means that the user can make a backup of all his files without much hassle, since they’re all in the same part of the directory tree. This, therefore, makes upgrades a hell of a lot less painful.
Installation of device drivers is more problematic, because a device driver does need direct hardware access. This can be alleviated by creating a special user with access to some of the files in the /dev directory and nothing else: Not root, but with direct access the system’s user shouldn’t have. If you both think that passwords are not acceptable, you can create passwordless accounts under UNIX with a predictable loss of security. But the beauty of this method is that the account doesn’t really have access to very much.
The idea that everyone will standardize around a single web browser and email program is a bit harder to shoot down, but I don’t think it’s the certainty dasgupta makes it out to be. For one thing, there won’t be any proprietary data formats or protocols. That means that people can switch between programs without losing anything. And for another, a lot of people do indeed like to make their machine their own, which is more possible under UNIX than Windows.
Now, these designs are my ideas about the UNIX that captures the nontechnical desktop market, not real comments on the various UNIXes that are in use by people like me right now. The UNIX I’m designing is essentially the same as the one sitting on my desk, but it is a long way from being an exact replica.