No. This is wrong. First the players don't have any right to input. The company owns the setting. Second, no agency is taken away since they never had any agency over the company's setting in the first place.
This. This right here. This is why Eberron is better. This to me reads as a dude in a tuxedo with a monocle and cigar saying "you don't have any right to the setting, I own it, it's mine, you're forced to go along with anything I do to the setting". Eberron, on the other hand, says "I don't care what you do with the setting, it's not mine, it's yours. Make it yours. Do whatever you want. Here, I've given you a bunch of mysteries to find the answer to, do whatever you want".
What the company did had no impact on my home game at all.
But it does impact the games of people new to the hobby. You don't know what it's like trying to get into the Forgotten Realms or Dragonlance after decades of novels, video games, and game products that are all "canon". The Forgotten Realms is drowning in metaplot and canon. Eberron does not have that problem. It recognized the problem that other settings have and took preventative measures to stop it from having the same problems.
That isn't necessary in every game, though, so it's not some sort of universal issue. For the many who like the changes, there's nothing to rewind.
You can include the metaplot in your game without the owners of it forcing the metaplot into the setting books. Eberron setting products will always start in 998 YK, just like the first Eberron book did 18 years ago. Over a hundred years has passed in the Forgotten Realms. Good luck getting newer players to do 100 years of homework in order to do a deep-dive in the lore of the setting.
And if that's what Eberron points out, Eberron is partially wrong. Metaplots may not be necessary, but their are neither good or bad. They just are.
And because they aren't actually problems of the other settings. They're personal issues. Either YOU like it, or YOU don't.
No. Quality exists. You can include things in your setting that are objectively bad and harmful to playing the game there.
That's what advice is for. The solution is not to ruin things for people who aren't making those mistakes and the ones who can and do learn from mistakes(and we all make mistakes). The solution is to give good advice to the DM on how not to make them in the first place. Advice, not changes to the rules or settings.
If the setting is "ruined" for people by having Elminster and Drizzt removed, they didn't actually like the setting as a game setting. They liked it as a story setting. Which is not prioritizing the needs of the game, and thus, bad for the game.
This is objectively false. The problem lies 100% with the DM who runs a DMPC. DMPCs are not setting specific.
Newer DMs often fall into traps that veteran DMs don't. Making the setting "stupid proof" is a good quality.
Show me your objective proof of that? Because all I've seen from you so far are personal opinions and unsubstantiated claims of "metaplot bad!"
Gestures vaguely at all of the discussions over the past decades of people angry that a metaplot ruined the setting for them. The Spellplague, the Faction War, the Prism Pentad, Die, Vecna, Die!, some of the sequel series of Dragonlance, and so on.
Clearly metaplots ruin the setting for people that previously liked it. Eberron cannot have that problem, because the creators have promised to never advance the timeline or include a metaplot. If that is the result of metaplots, it's better to not include them.