Word,
At lot of it has to do with the ever increasing power of computers.
RENDER limitation is the #1 problem everyone has. And ensures only Hollywood - with millions to invest in 100's of rendering computers - can create "Shreks"
But that is slowly changing. Especially with the new quads.
If the new Xbox comes with a far faster and more powerful processer (and memory) - the quality of games for it will also reflect that.
Also talent and development tools are also maturing. That has a lot to do with it too.
r