Performance is often taken into consideration for a game's score on the Visuals/Graphics, too.
If I recall, Dark Messiah definitely is NOT a great running game, framerate-wise and all -- the demo sure wasn't. Framerate was all over the place and I had to change some settings, to get it going decent and all. I'm sure by now, w/ patches behind it, it probably does run a hell of a lot better. (Please, confirm that someone!)
GameSpot really slapped NWN2 for graphics for pretty much the reason I stated above, the game not running so great, despite the fact it still looked quite good. Finally, w/ patch 1.03, NWN2 is running the way it should've been out the box -- and I can crank them visuals up, too!

I think GameSpot slapped also Gothic 3 for the same reasons, too -- saying it looked great, but the game ran all over the place, framerate-wise.