For me diminishing returns is beyond how the gfx look.
Throw $1,000,000 at building a super gaming rig and give a developer 100x more budget and you will see how awesome the game will look ONLY on that rig.
For me the point is when publishers started getting greedy through releasing broken game to micro transactions. This tells me that they do not want to spend anymore then they currently do in order to give us a full product because it takes more man power to make it a full product day 1.
This gen is where we crossed that barrier too far and we have all been buying games that will be broken in future as you need uge downloads which no longer will be available to patch the games. Sure the gfx are amazing this gen and ray tracing will make it even more amazing, but at what cost to the consumer in terms of cutting things out that foce you to download later?