The Q is interesting !! See, different people has different opinions. There is no concrete answer regarding ur Q. As my point of view, architecture of Linux is different from other OS. It is Unix like OS and need expert hand to handle this OS. Next is the security is a main criteria on Linux OS. Due to this point, Softwares are not installed previously..... and that is why, u may face problem to run multimedia applications specially movie files. U may face problems to run any data card / dongle for browsing purpose. U have to ensure all dependencies & other licensing issues before running. While Windows is so user friendly where u can get almost all applications running easily at least to compare with Linux OS. That is why, Windows is getting affected by virus very easily while chance of virus attack in Linux is so less or almost nil. There r several causes behind of ur Q as well as different flavor of Linux is also one of the reason amongst them, but it is true main problem is lack of Expertise on Linux systems.

Because decision makers in govt and business are overwhelmingly over 40; give the vast majority of over- 40 year olds a difficult problem and they'll reach for a piece of paper. They see computers as an adjunct to their problem- solving capabilities. MS Windows plays into this by making batch processing difficult to access for most users, reinforcing and encouraging this approach.
Younger than this people have grown up with computers as part of life, and see them as the best way of doing the heavy-lifting aspects of complex data management. They're also less fearful of change, and Linux on the desktop is a change.
IMHO, nearly all reasons usually given are a mask to hide this issue.