In my book, this is the only critical reason to live in the Apple or Microsoft universe. Lots of applications just don't have native support for Linux. It's becoming less and less of a concern to the average user since so much has been ported to a browser environment but it's still a concern. I use some desktop CAD software that forces me to have a Windows PC at home. I still haven't found (or truthfully, conquered the learning curve of) any application that can do what I do with that software.
I try to keep an open mind while at the same time using the tools that work best for me. What I like best about Linux is that it doesn't tie me into anything proprietary but everyone has their own opinions and there's nothing wrong with that. It'd be a boring world if we didn't have options.