Honestly that’s a pretty good argument for the differences UDK-UE4. Balancing stylization with PBR accuracy has always been a challenge, and I think there is a level of extra life to be found in handpainted textures even when things were otherwise quite inaccurate.
And to your point on scalability, the callisto protocol people gave an awesome SIGGRAPH talk, with most of it being dedicated to the danger of misapplying PBR principals and getting bad art as a result. Your lighting and your shading models both need to be correct for the final product to be, and having a great lighting setup interact with bad shader models will still result in a bad final image. The Callisto team reminded people that since PBR is imperfect, you need to be able to tweak things to account for when it gets things wrong.
I think that real-time GI really was an essential piece for bringing lighting all the way to where it should be, but as the Epic team reminded people in the first lumen talk, PBR values won’t necessarily give good results: you need to brighten the albedo to really get a kick of GI. I think that one of the reasons UDK may feel better is that a lot of developers still aren’t totally sure how to stylize in the framework of PBR.