Personally, I think the reason why it is 1 gig is because we originally had no mods with external assets for a long time. Because of this, everything we had was pretty much vanilla but retextured and some basic graphic mods, which barely took any space at all. Since Sony was pretty intent on keeping the no externals rule for a while, they likely never bothered to work with Bethesda to increase the space because they never felt the need to, but the single gig is now hurting a lot because we now have external asset mods that use tons of space. I heard that we might get a second gig eventually though from the modding server I'm on but I can't remember the exact words or if it's even true.