Yeah, maybe normal people's thoughts fly to the many viruses they caught while using their PCs, when they read "Microsoft", but they know it's their fault and that there are antivirus programs. Switching point of view, what comes to people's mind when they hear Linux? Nothing, for the majority, and "hell no!!! That weird geek stuff where you can't even install programs with a simple double click" for many others, me included (I'm very experienced with Windows and tech-products but hey, isn't it ridiculous that I couldn't easily install nvidia drivers on my laptop, using Ubuntu (supposedly the most user friendly of all Linux distros)?
Anyway, just wanted to say that in most people's mind Microsoft Windows == computers, they don't consider anything else.

With regard to downgrade from older Nokias, when buyinv a WP7, not true: as someone said above, people look first and foremost for a smooth phone. Secondly, they open the market and download few apps like Whatsapp. And they're happy. Sad, but true. I thought the same as you guys some time ago, but then I realized that the majority of people still goes around with a mp3 player and don't need a SD card; barely anyone uses BT transfer, so they don't care it's close; and so on. Besides, iPhone doesn't have all these and none of the normal people seem to care, so it has become the standard.
Finally, I read many forums and noticed that most of the people who switch to WP7 from Android are happy and like it better, to my great surprise. I myself owned a LG Optimus 7 for some time and I certainly like WP7 more than Android (had a LG Optimus 2X), for it's more polished, smooth, consistent in the UI (one of the biggest problems in Android: it's ****in ugly) and the shortcomings are minor and you can definitely live with that. I'm not a super geek so I didn't miss devel-su and other stuff therr, but I can say that normal daily usage does not require any of the features that WP7 doesn't already pack.
That's why maggots do and will like it, and imo it will grow in the future.