Because 16x9 is the aspect ratio of HD television so it means you can watch video in 1080p on your device without black bands on the top wasting precious video screen space.
Showing a 16:9...
FYI: The building in the lower right should be Building 3 not a second Building 8.
Seems like a good request to send to the paint.net people. It'd be nice to see a "UI formerly known as Metro" version of it.
Seeing that the original Surface Pro (and all of Microsoft's other pen systems dating back literally over a decade) have had palm rejection, it's a pretty safe bet that Microsoft didn't forget it...
Here's a list of Ford cars/trucks that have Ford Sync (based on Windows Embedded Automotive) available. You'll note the Ford Focus is on that list.