In regards to an 11 tear old knowing how to change file extensions, good for him. I still ask why does he have to do it in the first place and how exactly is that user friendly or beneficial for the average soccer mom?
Okay, I can agree with you on the point that MS shouldn't have set a Metro app as the default picture and video viewer for the desktop. For everything else, you're just hammering the same point over and over again, ignoring anything that doesn't perfectly conform to your idea of the perfect tablet.
First off, changing file associations is super easy. If you install any program that can open certain things, a big black box pops up in the middle of the screen with a list of applications after you first run it asking if you want to make it the default for this type of file.
Yeah, this might be a little convoluted for a soccer mom, but guess what? If she's using RT, it won't even matter. The only application that uses the desktop on it is Office, which as I said was stupid. For everything else, she'll be spending 100% of her time in Metro, using it about the same as she would iOS.
Lastly, the Surface crashed on a Microsoft exec while he was demoing the Surface, but according to you these things just don't happen.
God forbid beta hardware running beta software still half a year away from release messes up on someone.
Similar things have happened to Steve Jobs and crew during his keynote presentations in the past. Like laughing about a program crashing, or him making everyone shut down their phones so he could get the brand new, never before seen iPhone because he was having trouble getting it pick up a wifi signal.
These things happen, and don't speak of the final quality of the product itself.