I thought I'd better respond to some of these comments...
B!nej: True, there are different types of users, but it's entirely possible to set things up so that the "casual user" can just power-up and go, while allowing the "dedicated user" to flick a switch and get all the power. If the preset configuration is adequate for the casual user, they won't get frustrated and confused (cf Corel Linux); however, the dedicated user can still jump in and configure things relatively easily to their taste. Same things go for developers.
Microkernels: AFAIK, one of the selling points of microkernels has been the supposed stability due to the protection-ring structure preventing, say, floppy drivers from crashing the core kernel. Also, WinNT may say it uses a microkernel, but it doesn't. The whole kernel (and drivers) occupy the same address space, and can walk over each other quite easily.
The SGI box: That's exactly what they did; attached a big metal bar across the access plate. Sorry, probably a bad example.
Backward compatibility impedes the ability to completely redesign things, thus making change harder, hence making modularity harder to implement.
Networking pipes: The point I was trying to make was the difference between functional and procedural programming languages.
Linking to KDE: But why does the clock program have to link to KDE at all?
samiam: There are so many specialised programs out there that don't need the other pieces gnome adds. Clock programs barely need any configuration.
Priyadi: I'm not saying that the shell should support networking by itself; it could quite easily be configured to launch a given utility to do it for it. Also, good modularity would mean that I wouldn't have to care about which protocol to use, nor would the shell. The shell should simply hand control over to a program that can decide which protocol/port is the best to use (after considering speed, network load, security, etc).
Okay, I admit that the networkable-pipe example was probably a bad choice. I should have made it more clear that I know it's currently possible; it's just not convenient or simple.