I've found that people use windows because to most, a PC is windows. It's compatible, it's familiar, and it's frustrating, complicated, obfuscated, and they don't trust it. Tablets are an escape from that. They will probably keep a "PC" around, but the tablet ( android or iOS) is an escape from that frustration.
Why, when that customer walls into bestbuy, would they choose Windows, if that is the experience that they are actively trying to avoid?
The only thing that a salesman could say to sell one is "well since its Windows it will run all the software that you spent so many years learning and let's face it, you've become dependent on that , so what size do you want?"
Instead they have to say "well, no it doesn't run anything, at all really, have you checked out Android yet?"
This can't be a surprise to anyone.