you raise a good point but the NUC isn't a *desktop*. It's a small x86-64 box, not much bigger than a vhs cassette, that screws into the back of a monitor.
This is designed for large corporates with lots of cubicle monkeys for whom performance of those Core 2 Duos from 7 years ago was sufficient but they want to save a heap of money on electricity bills. These will be popular when adopting Windows 10. XP --> 10, HDD --> SSD and with better integrated graphics. Did I mention the energy savings?
Relax, you can still buy a performance smashing i7 residing in an enormous watercooled tower if you wish.