This song gets played on forums like Ars Tech about a dozen times a day, but let me give it a shot.
Apple was/is in the hardware business. They have, since 1977, been concerned primarily with selling Apple computers. They have at various times over the years provided free, then later charged, for an OS and for applications software.
The Mac OS, for example, was free until System 7.0.1. In the bad old days we'd stay up late, late downloading a new update from CompuServe at 300 or 1200 baud for hours to get the free updates. CompuServe, of course, collected their regular $12.00 per hour.
Mac OS X, no more, no less, is designed to sell Apple computers. They give away certain applications software which is really quite superior when compared to similar software on the market called iPhoto, iMovie, iDVD, and iTunes which, over time, have become rather sophisticated and powerful applications software.
At various times they have created and sold certain software, FileMaker Pro (actually sold by a spin off co.), Final Cut Pro, etc. But the sale of applications software accounts for well under 1% of Apple's gross and OS software for little more than that.
An Apple computer to the CEO of Apple has always meant an Apple Computer running Apple
proprietary software. It is not especially easy, if you have the parts, to even build a Mac. In some cases you can't get the right OEM CDR/RW drive or whatever even if you have a mother board, the "right" monitor, and all the "right" cables and such.
Apple has only shown interest in promoting clones (officially) and the company very nearly went bankrupt. The year was 1977 and that's when Steve Jobs returned to Apple. The clones were built in many cases with parts purchased from Apple and in all cases with parts built to Apple specifications.
All Compaq had to do circa 1986 was reverse engineer the simple and limited function IBM PC ROM and they were in the clone business selling the same OS that was written for IBM originally for sale in 1981.
The Mac OS is now far less dependent on the code in ROM but it has never been reverse engineered and the OS X GUI is just as proprietary as OS 9 or earlier system software was. Apple wants to sell you a computer. If you want to run OS X buy a Mac. If not, you're out of luck and should best pursue some form of KDE and Linux.
(Anything but Micro$loth.)