The answer is always "Because I'm learning cool new shit and enjoying myself".
You know when the last time I even thought about my OS was? Probably 8 yrs ago. I'd much rather fiddle with the stuff I'm building than with the stuff I just need to work in order for me to build what I'm building.
So I have no aversion to learning, but I want to focus my time learning the stuff I want/need to learn. And if there's an OS that runs well enough I don't need to think about it then that's fantastic.
The argument is that if you're going to try Linux, it's only fair to give it a fair shot at adjustment, rather than complaining that it doesn't work like you old OS, because guess what - it's not supposed to.
To be honest, I hadn't really given much thought to my OS for even longer before I decided to go looking myself, I'm glad I picked that fight though. Granted, 8 years ago I was 15, digging in to the guts of an OS for the first time is very different from focusing your time to build what needs building :)