That's what Jobs calls controlling the "whole widget." It lets Apple limit the number of drivers it has to deal with, and to drop support for legacy hardware standards in a shorter time span than Microsoft can; for example, dumping ADB and serial in favor of USB. It lets Apple avoid the kind of code clutter Windows has to deal with, and makes the experience more elegant.
At home, I have a 20" Dell flat panel (as the main of three monitors). At work, an Apple 20". The displays are virtually identical -- I think they both buy their LCDs from the same supplier -- but on the Apple I never have to navigate through menus or use buttons on the front to make adjustments. It's all done in software.
Is that extra level of elegance always worth the cost ($500 vs. $1000 at the time)? Not always. That's why I have the Dell at home. But if I still worked in a business where color matching is critical, the Apple would win hands down.
Note that I am using the word "elegant" -- the adjective that best sums up what separates Macs from Windows -- not to mean eye candy, but in an engineering sense. A minimum of clutter, no unnecessary parts, tools to do what I want to do and then get out of the way.
True. I'm reminded of recent articles on M/S Vista using BIOS instead of the newer EFI for the boot process. Compatibility with legacy systems can make for an engineering nightmare.