I'm sorry, but anyone stating it's low-end PC's that are at fault are really struggling to justify the graphical downgrade.
The simple fact, is this has been happening for the better part of a decade. Look at other games in the past. Watchdogs, a prime example of designing a game's graphics to work on a high end pc, for PR shots, then downgrading the crap out of it to make sure it works on consoles, and only allow the PC version minimal upgrade options to ensure parity - which supposedly ensures sales are not affected by disgruntled console owners - of whom there are more of.
Assassin's Creed games - all suffered from the same thing. And for the exact same reason. Even The Witcher 3, which as a franchise started out as a PC only game, ended up being 'downgraded' graphically to work on consoles by the 3rd game.
It happens, and it happens exactly for the reasons given. Of COURSE you need top hardware to run games as good as they can look, but why on earth they can't KEEP these assets ingame, and THEN downgrade them to work on other machines is beyond me - except for the marketing thing, as mentioned. I mean, pretty much all games are DESIGNED on PC in the first place, then once the art assets are complete, the coding for the effects are done and the prototype is up and running... then they begin the 'optimisation' of the game art, effects and general coding, to ensure it runs at a steady rate. And until the PS4/XboxOne, that usually meant 30fps with a LOT of fidelity loss. Of course, the high end PC could run the original code and assets just fine, but because a lot of people don't have the required hardware to run it, then the PC assets are just swapped out with the new 'improved' console ones.
It's a reason why PC porting is so poor. They code FOR the graphics engine of choice, then downgrade to the console, and then port THAT version back over to the PC.
(I am of course simplifying the process here, but that's pretty much the end results).
Frontier are no different. The excuses given for the various downgrades JUST before the XBox version came out were just that. It was abundantly clear that the fidelity and detail of a lot of assets were reduced, to ensure that the game looked good on both console AND PC. The planet beigification was clearly a result of Horizons, there was no way those original planets could be rendered in such exquisite detail when actually ON the surface, but as we've seen on many other PC demos, PC's are quite capable of rendering such complex scenes - consoles, however, are not.
The usual crowd are going to 'virtually' downvote me, and that's fine. Frontier, if they decide to comment (which I would imagine they won't in this case) will deny everything - they're not exactly going to come out and say 'yes, to ensure the game runs on all platforms equally, we had to optimise the graphical fidelity of the game'. - that's a PR disaster.
But please, folks, don't insult intelligences here by suggesting downgrading doesn't happen. It does.