I know why Linux hasn't gained mainstream popularity with the normal consumer. And i know why it never will.
It's because it doesn't cost anything. People associate a higher cost to higher quality. Because Windows 7 Ultimate has a price tag of A$268 the normal consumer will identify this as superior in quality than, say, Linux which is completely free.
Also lack of advertising from a major corporation like Microsoft means Linux has no awareness to the normal consumer.
Basic micro-economics
Yes, and there's also the same reason that so many people still use Internet Explorer - the computer came with it and it works, so what reason have they got for changing it? Even online it's still very hard to find PCs which are supplied with Linux. If people were more aware and were offered their laptop for €50 less than normal because it has Linux instead of Windows on it, more people would go for it because 50 quid is 50 quid, and all they're doing is looking at Facebook anyway, and Farmville is as adventurous as their gaming gets. I do appreciate though that this would need lots of investment from PC suppliers though, for technical support staff and for marketing, and again, why would they bother when Windows works adequately?