The way I see it
Microsoft supplied the first consumer OS by default, because that was all there was, people used it at work and therefore it was the only option for the home. I won't mention that often they did not have a windows/office license as they got it from work.
Home users for the *MOST* part use the web, email and some other small tasks, that's why they bought the thing in the first place. Along comes the tablet and they do the same quiet adequately for their needs, why buy a PC and have to purchase Office & and an OS?
Microsoft wakes up, they are bleeding sales, consumer sales, business is in recession and hanging on and getting the most from their existing infrastructure. Therefore MS brings out an OS that is designed to entice consumers more than business, but the market is not the same as 10 years ago.
If my mom wants a new laptop at 75 she will get a Chrome book, her home laptop gathers dust for the most part since we bought her the iPad. Once she used the laptop everyday for an hour or so, now it is the ipad and it is used almost all day between her and 78 old dad(who would not touch a PC)
Anyway just some ramblings