Don't forget Nokia has been a huge worldwide brand, and previous dominator of the low price market.
The name is instantly known to most people, the only problem is that it is known as a big name from the past.
It's hard to think of buying a business in decline as a smart move.
Then you have the problem of such a well known brand taking over Nokia... If MS took over the Apple brand would people assume nothing would change?
I think most people will think MS is going kill any desirability left in Nokia.
But... Time will tell, huge restructuring etc and a fresh face for CEO?
Problem is, Nokia had a very strong brand image, at least in europa, for quality, durability and ease of use even if a bit ugly. There is still customers here that dont want to hear about anything but them.
That is a brand image that you cannot associate with Windows imho, and this move is the death announcement for Nokia branded phones. And a brand image, especially one as positive as that, is something you work decades to build but can lose in one bad move.