The problem as I see it is that there is an upper limit on how good any game can look graphically. You can't make a game that looks more realistic than literal reality, so any improvement is going to just approach that limit. (Barring direct brain interfacing that gives better info than the optical nerve)
Before, we started from a point that was so far removed from reality than practically anything would be an improvement. Like say "reality" is 10,000. Early games started at 10, then when we switched to 3D it was 1,000. That an enormous relative improvement, even if it's far from the max. But now your improvements are going from 8,000 to 8,500 and while it's still a big absolute improvement, it's relatively minor -- and you're never going to get a perfect 10,000 so the amount you can improve by gets smaller and smaller.
All that to say, the days of huge graphical leaps are over, but the marketing for video games acts like that's not the case. Hence all the buzzwords around new tech without much to show for it.