Technology has slowed down, but there's also diminishing returns for what you can do with a game's graphics etc.

• The original Halo ran at 480p on the Xbox. 4K UHD has 27 times the number of pixels as that. The resolution increase from the NES to Halo was about 5.35 times.
• Games nowadays on PCs are often capable of running smoothly into the hundreds of frames per second, but of course for example the difference between 21 and 30 FPS is more noticeable than the one between 231 and 240 FPS. (Looking at you, OoT)
• Render distances are much larger with less obvious compromise on LoD.
• Stuff like ray-tracing is of some graphical benefit but is hugely computationally taxing, and there's nothing you can do about that. It's just more diminishing returns.
• Physics engines are much more complex.
• At some point, a limiting factor just becomes art direction and budget. You can have all the fancy techniques you want, but you still need to make detailed textures, animations, etc.
• The amount of polygons starts to hit a ceiling too where the model is basically continuous to the human eye, so adding more polys might only help very subtly.
• Color depth is basically a solved problem now too compared to going from the NES to the Xbox.

You can think of sampling audio. If I have a bit depth of 1, and I upgrade that to 16, it's going to sound a hell of a lot more like an improvement than if I were to upgrade from 48 to 64.

It’s interesting how much technology has slowed down.

We haven't slowed down. We simply aren't noticing the degrees of progress, because they're increasingly below our scale of discernment. Going from 8-bit to 64-bit is more visually arresting than 1024-bit to 4096-bit. Moving the rendered horizon back another inch is less noticeable each time you do it, while requiring r^2 more processing power to process all those extra assets.

No we’re getting close to some 20 year old games still looking pretty decent.

The classic games look good because the art is polished and the direction is skilled. Go back and watch the original Star Wars movie and its going to be more visually acute than the latest Zack Snyder film. Not because movie graphics haven't improved in 40 years, but because Lucas was very good at his job while Synder isn't.

But then compare Avatar: The Way of Water to Tron. Huge improvements, in large part because Tron was trying to get outside the bounds of what was technically possible long before it was practical, while Avatar is taking computer generated graphics to their limit at a much later stage in their development.

Same with movies. LOTR is almost 25 years old and still looks great.

True. Was playing Arkham Knight the other day and thought this nine year old game looked better than at least half of current gen games.

Last time I was amazed with graphical progress was with Unreal in 1998. And probably just because I hadn't played Quake 2.

From then on until now it's just been a steady and normal increase in expected quality.

Doom 3 might have come close (and damn, that leaked Alpha was impressive) but by the time it was released it looked just slightly better than everything else.

Damn, should have scrolled farther before looking this up myself.