Dont know the achitecture of the ipad/iphone massively well, but I'm sure the graphics processing will be done on a dedicated chip rather than the A5 processor? In theory you are right, they could make it all more powerful - but that will drain the battery quicker and produce more heat which would have to be managed. At over full HD res, you'd have to ask why. I think they will aim for full 1080 HD res next so they can support movies. It wasnt long ago that PCs struggled to handle that res