We live in an age where flatter, more consistent UI designs are a necessity. Not flat to the point where you can't tell what the hell is going on, like Metro, but minimalist with visual cues to let you know what is happening, which is similar to Google's interface for Android and their web services.
We don't need to be reminded that games used to be played in casinos. We don't need to be reminded of how a ledger notepad with leather binding looks. We don't need to be reminded of how a bookshelf looks.
Why?
Because we don't use bookshelfs, game tables, or ledger pads on our phones.
We use digital representations of games, text, and input devices. The need to have an analog analogue is gone. And apart from the horrid icons in iOS 7, it's a step forward in every way. Except, of course, for the icons.
Did I mention the icons were awful?