Apps (Score 2, Informative)

I believe, the main reason that Linux hasn't taken off on the desktop is the lack of mature open source apps. Desktop users tend to use and have invested in many applications to do whatever it is that they do (i.e. productivity, internet, games, photos, etc.). It takes time to offer solutions (Wine, OpenOffice, etc.) that are as robust (or robust enough) and make it inexpensive and easy to tranfer data and the occasional Windows app (games) to a Linux box.

There is cost (which is slowly declining over time) associated with a transfer from Windows to Linux.