Without having a PC release here to actually scrutinize, I think it's kind of silly to blame From for potentially downgrading versions that might have never been upgraded to begin with (talking PS3/360 console release). I think it's fair to call them out on maybe not clarifying that the consoles wouldn't match the preview or PC version (assuming PC ends up looking closer to the preview shots) but it's also not too uncommon for preview builds to reflect a version of the game that is often only seen on high end PCs.
And as far as I can tell, these two videos from the Executioner's Chariot boss fight, one from the network test and the other release, both have lighting that looks exactly the same.
http://www.youtube.com/watch?v=MFVzBEcdkg4 - network test
http://www.youtube.com/watch?v=lwDNNuPVv3E&feature=youtu.be - release
So I don't really understand the claims that the game was downgraded from the network test version.
I think I'll hold off on my judgement until I see the PC version before I determine how much of the preview stuff was true or just bullshots.