Tablets were invented for consuming media; as movies and books don't translate well on the phone-sized screen. They were also invented for showing executive presentations in a stylish way. Beyond that everything else is just a rehash of existing uses, most of them done with the tablet on a stand, on the lap or propped up on something.
Try playing a game holding a bag of sugar upright and your wrists will collapse within days, or you'll end up like Popeye. Also, if you do want to play games on an existing tablet there is a lot more screen space for the soft-controls and buttons to be placed, so the gaming action isn't obscured by sweaty thumbs.
So, Sony are two for three this year, and this tablet is the unfortunate turkey in the pot. The PlayStation brand is at risk if Sony starts throwing it at all kinds of mad ideas and here's the perfect weapon for anyone with an axe to grind.