1. While the hardware and performance are amazing, the user interface is the opposite. Imagine buying a luxury car with amazing performance only to find that simply opening the door is a royal pain, each and every time.
2. Apple will downgrade the usability over time. A year from now, or two, Apple will downgrade your user experience. Imagine that in your luxury car you can see out the windshield, but the dealer insists that you install a new upgrade with a heads-up-display that cannot be turned off.
3. Apple will degrade the performance of your system over time by constantly introducing more features which require better hardware. Your sleek and fast computer will eventually become unusably slow.
4. Apple profits from preventing you from using the computer you own with other software, for example Linux. When your computer cannot run Mac OS (see #3) above or you get sick of the "features" (see #1 and #2 above), you will not be able to do so. The reason for this is if you could try Linux, there is is a strong possibility you will see just how user unfriendly Mac OS is and never go back.
5. You care about the environmental impact of your purchasing decisions. You understand that because you are not able to upgrade the hardware and operating system, your purchase is very likely to end up in a landfill.