Most of the end-users in various corporations and most of the Asians working in the IT industry grew up using windows and its derivatives. For a vast majority of the people in Asian countries, Win*.* was and is free because piracy knocked down the cost of the computer.
Also, most of the end-users bought windows based machines when they were in School because the games were available on Windows and for most, at that stage in life, the computer was just an entertainment device to be used for gaming, music and movies.
With the increase in adoption of Linux in Schools and the qualitative jump that Linux has experienced in the past few years, you shall see increased adoption of non-Windows OSs.