We need to build a rich set of patterns for the design of user interfaces, by taking the best applications and seeing what makes them so.
We can borrow concepts from the architectural patterns. Town square = desktop, where everyone needs to go to use the essential services of the city. Applications = buildings, where you go into particular ones to perform the things you need. We can certainly build like this.
And just as you wouldn't let an apprentice make the front door of the cathedral – you may not want J. Random Hacker to touch critical code. But you can train him, up the way through journeyman and up to master, so that he can build great things in the end.