ok first, the textures they're using are way too small and detailed compared to wind waker, windwaker's grass was basically plain green (I realize in a top down perspective more detail is needed) but they went overboard with the detail, and the textures are too damn small, they're so repetitive.
then, the fact they're using 2 polys for each square of texture, which is a huge waste, ie:
a hallway in a logically made game would be atleast 12 polys, in phantom hourglass, it would be hundreds, even thousands depending on the length