In theory? Or in reality? Because these are 2 different things.What makes a foldable iPad attractive? Genuine question.
In theory, you can have a large iPad (which is more usable, because it's large) that is more portable when folded (because it's small).
But that's about as far as the theoretical benefit goes. In reality, the very idea gimps the product as it has to be entirely designed around this. The creases and hinges are nightmare additions. The more portable shape is still much larger than a pocketable device, so it's not really more portable at all. If it has to go in a bag instead of a pocket, who cares how big or small it is when folded. To make it pocketable means the unfolded state is still way too small to be useful. It basically means an iPad mini that is folded in half to fit in your pocket. But who the hell wants an on-the-go iPad mini? Hardly anyone, by virtue of its sales history. The end product is too large to be an iPhone, and too small to be a (good) iPad.