Linux has way too little market share on the desktop anyway. Especially when considering that it does all the things the average consumer wants, ever since hardware compatibility problems have virtually gone away. I think the main reason is actually, that "the computer" with its OS and everything is one product to the average consumer. They buy a PC, it runs Windows. They buy a Mac, it runs OSX. And it usually stays that way. Pre-installed Linux was never really given a proper chance.