But for people who value specific software that is OSX-only or some of the features only found in OSX (like CoreAudio for music stuff) or the general interface polish and perceived stability, it doesn't matter if the Apple option costs $2000 and the other brand/build with similar core components costs $1000. If it doesn't run the platform you want/need then it doesn't matter that it's more bang for the buck.
Basically I default to Windows because for the things I do on a computer, it's got the most flexibility and options for hardware and software. Linux is missing too many applications I need/want and OSX only runs on machines that cost a good deal more while offering nothing I really need enough to justify the cost. But when I've needed or wanted to run an OSX application in the past (Final Cut Pro in my case several years ago) it just wasn't a question. The stuff I wanted to run and the hardware I needed to hook up required OSX so that's the only reason I shelled out for an Apple computer. If I could have done it without OSX I'd have saved the dough and put it into something else.