Looks like Sony is modelling PSN after Steam, no surprise there. As far as textures are concerned here's a simple explanation: Let's say you have a square texture of side length X and area A. Now you want to double the side length (resolution) of the texture to be 2X. The new texture's area is 4A. Meaning you need four times the space to store it. I'm fudging it a bit because compression often let's you store repetitive data for free, but that's the gist of it. I would also imagine that, given that developers now have 50GB of blu-ray to play with, they aren't bothering to compress the textures all that much because compression still introduces artifacts which can easily be seen at high resolution.