I think all of your points are true for badly made UIs, regardless of if they are flat or not. I like flat UIs, partially because they look and behave like digi

I think all of your points are true for badly made UIs, regardless of if they are flat or not. I like flat UIs, partially because they look and behave like digital things instead of trying to resemble something else and partially just because they usually (entirely subjectively) look better. We have a deeper well of inspiration to draw from for non-flat and more experience with them (so it's easier to make them "better") but I don't think anyone can say they are inherently "better".