I think people like to support the "underdog". Whatever is popular will inevitably have people that rebel against that popularity. Maybe it's a bit of the hipster attitude.

I use a MBP for work, and while the build quality is great, I find the machine itself to be...meh. My older one had more ports, some that I used often and still miss. I would never have a new Mac for that very reason. The OS is decent, usable certainly, but I really would rather be using Linux. I don't have any very strong opinions though. I'd be fine with any machine with a unixy OS on it.

I think very strong, hardline opinions on this kind of stuff can sometimes betray immaturity. The world is rarely "black and white".