OK, seven words:
Where the fuck are the bump maps?
I mean, everyone is all in a snit about how flat it looks relative to Diablo. Some good bump mapping on the surfaces -- so directional lights would give some etched-stonework quality to what is indeed a pretty flat and painted-on look, relative to Diablo -- would work wonders here.
It probably doesn't fit in their rendering budget for the ultra-low-end they're trying to scale down to, but damn, it would definitely add a lot of roughness and grit to the environments, which I agree they are profoundly lacking right now.