I'm curious now what stops people from using Linux on the desktop. There were significant issues a few years ago, but they now appear to be addressed. What are the problems with Linux on the desktop?
Don't get me wrong: most of them, like KDE and Gnome, focus on some user, but that user is themselves, developers, open-source enthusiasts, etc.
All Linux desktop environments look really, really bad by default. Even Gnome 3, Kde 4 and Unity have terrible defaults, like icons I would be ashamed to draw on a high school art class (not that I would do better, I'm no designer, far from it). Also, there's no way to get a consistent looking desktop if you don't stick to the default applications. Having GTK and QT apps to look well together involves a lot of forum-reading and googling, and it's never 100% decent.
Usability only fits a very narrow category of users. Both Gnome and Unity have completely disregarded the Desktop community and shifted to either "tabletish" or "keyboard-driven" interfaces, something too many users simply don't feel at home with. KDE, while choosing to stay more on the classic "windowish" desktop, have been a complete unfocused mess of a project.
Then, for a third and last example, there's the lack of decent apps. All the commonly used apps for a Linux desktop user are usually "good enough" for what they're supposed to do, but none are really, really great. LibreOffice does the job, but it's a decade behind even MS Office. Linux ports of commercial apps are usually hideous and lacking features.
Bottomline: Linux desktop environments have been playing catch up with the commercial desktops since forever, but keep doing the same mistakes. Most distro's tried to copy the "App Store" model, for instance, but have done so terribly enough that I still find myself installing "Yumex" or "Synaptics" everytime I build a new machine.
There are, however, people going in the right direction. I've been watching projects like Deepin, Elementary OS and Solus - and I honestly think they're trying hard to do what bigger projects have been failing at. Maybe they'll stand up, maybe their ideas will be merged into the bigger boys, but it's good to know someone's actually trying.