I don't think those are the real reasons for using Macs. The real reason is that if you want a premium laptop, the only option you have out there that isn't compromised in any way is a MacBook. It's the only way you can get a high resolution screen, PCIe storage, Iris/Iris Pro graphics, a quality trackpad and top notch build quality in a single package at a reasonable price. Even if other OEMs come close on these points, they'll either cut corners somewhere or price it way beyond a Mac. The popularity of Macs is indicative of the garbage in the rest of the market. At this point the only other laptop I would even consider is a Razer Blade.

The other problem stems from Linux itself. In 2014, you still need to wrangle with the terminal to get certain drivers working correctly. Even if you do get them running, you're still stuck with inferior performance and lower battery life as compared to Windows. This is particularly true for GPU drivers - whether closed-source or open-source, they suck a lot. On a Mac, the driver setup and optimisation has already been done for you, leaving you free to get on with your work straightaway. You get great performance and great battery life out of the box.