Planet generation in the old Horizons was extreme to the point of unrealistic in many cases, the earth for instance is effectively as smooth as a billiard ball, seeing huge valleys and mountains from orbit or further out is something you just wouldn't see in reality, yes the extremes were fun sometimes, but what Odyssey actually has now is far more likely the sort of things you will see in the galaxy if you could get out there.
This is the issue with space in general all those NASA nebula/planet photographs that are color graded and not how they would really appear has really shaped how people think of and represent space in other media.
In games especially I think the heightened reality aspect of it is important since you can't recreate it at a high enough quality and you want to give the players the awe-inspiring experience of walking on another planet instead of just a barren desert wasteland or black empty space. I initially disliked the more cinematic color tinting in Horizons when it was added but it certainly achieves a better effect than the PBR stuff that just looks boring.
Not having an usable planetary scanner that breaks apart the biomes for you to entice you into dropping from orbit and checking out some cool terrain features (I mean like telling you "hey the thing you're pointing at is a 5km high mountain or a 30km wide crater or whatever geological feature").
I also wonder if a lot of the disappointment of "it looked cool from far away but when I landed and looked at it up close was flat and boring" is caused by the terrain sinking effect when replacing low quality terrain with more detailed versions. It's obviously not implemented well when you can see it, but in those cases maybe the more jagged low poly version was actually more interesting to players than the smoothed out high detail one.
Odyssey should have gotten players to land on more planets to check them out up close to find the supposed smaller cool terrain features that now exist without needing the exaggerated mountains, craters and canyons of Horizons. However exobiology just wasn't implemented well enough to achieve that with many of the plants spawning in boring flat areas and not requiring enough travel to really give you enough of a shot at finding the cool terrain stuff. The cool rare stuff players have found in odyssey is still large scale (Ice mordor).
Ultimately everything is still based on heightmap based terrain and that's just not interesting or impressive enough on it's own anymore, especially if you're limited to barren lifeless planets. Even if it looked better, was more polished, didn't have performance problems and lighting/shadow issues.
I don't think the planetary generation was ever touched once the galaxy was rerolled on the Odyssey release; what might have changed is the rendering quality, so you get a bit less morphing when you skim the surface. But the planet generation in principle is what it is since Odyssey released.
The meshes remained the same but the coloring was changed a bit so canyons and such stood out more. The performance slightly improved may have caused people to turn up their graphics settings that makes more details show up from distance or even when in orbit so they notice it, but that's about it.
While the game mostly generates and renders planetary surfaces extraordinarily well, one thing that has always bothered me is that I have never seen extremely high mountains and extremely deep valleys. There are mountains and valleys, but they all seems to be quite shallow. The tallest mountains I have seen are like maybe 1-2 km high and that's it. (I haven't actually measured them. Should be very possible using the ship's altimeter. Maybe I'll do that one of these days.) If they are actually higher, they don't look like it. Have never seen an Everest-sized mountain anywhere. Not even close.
There are high mountains, but the issue with that is that the ones that most stand out to most people are usually the ones with incredibly sheer drops.
Really big mountains could actually look pretty flat from the surface (Olympus Mons) and I don't think the odyssey terrain engine allows for features that big organically - craters and canyons spanning multiple tiles are probably added after picking the tiles on a different pass over the generated terrain and and the tiles themselves aren't big enough to have massive features like that.
Are they still working on bringing planet generation back up to the level of uniqueness that horizons had or did the dev team become lazy.
Confirmed no, from here:
https://forums.frontier.co.uk/threads/issue-tracker-planetary-tiling.602191/