Years ago, when I worked in a PC only shop, people asked me what computer I used at home. I replied that I use a Mac. They were incredulous. When they asked why, I replied that when I go home, I didn't want to have to work. Based on this Quora reply, I'm not alone.
Answer by Ansel Halliburton:
I have built PCs and Linux boxes from parts. I built and ran a distributed Linux cluster. I had a few flavors of Linux on a laptop at a time when it was non-trivial to do that. I can handle running Linux just fine.
But now I choose not to. I have a Mac.
Why? I just don't have time for that stuff anymore. I am at a place in my life where I will gladly pay more money for a product of higher quality that saves me time because I am (1) really freaking busy and (2) not broke anymore. I need a low maintenance, high performance computing tool. Mac OS X and most of its major applications are well integrated, very high quality tools. Macs are also beautiful and shiny, and I like that as much as the next person, but it's secondary.
As for the question's premise that you can get as good a UI in Linux as you can on a Mac, that is just not true. Yes, there are some very shiny Linux distros and window managers out now. But the quality of third-party Linux applications' UIs is, generally, still poor—certainly not on par with the average UI quality of Mac applications. You have to look at that when considering an OS because without third-party applications, the OS isn't going to get you very far.