I'm actually really impressed by GT's choice. Seems they acknowledged that high-definition graphics doesn't automatically equal high-quality graphics (although the other nominees don't lack the quality).
Reading the comments on there is really funny, too.
So many people trying to reason, that only the most real looking games deserves a graphics award, as they represent the highest technical achievement. A pity, that we won't be able to tell shooter game A from shooter game B, if that trend on the high-def machine continues. Not that I have something against all those gritty games in their epic browns and grays. ^^