It helped to sell more consoles and more of the first chapter, it doesn't damage the franchise or the sony's image.
I acknowledge both as reasonable explanations, even though none of them convinces me much... because it may seem that in ND they don't know what they're doing, so to speak. I don't think a bit more fog and a couple of shadows can dramatically help on the sales of consoles and previous games, either.The tale grows in the telling.
There needs to be aesthetic consistency across the entire game and if a scene or level - which may have been added relatively late in development - chokes the engine, it makes sense to tone down the causes.
It's just... meh...