Bethesda fixed past mistakes by implementing Broken Steel, a DLC that allowed us all to continue playing past the end of the story (with a modified ending). I think this is a great idea and should be considered by Obsidian, since there's a lot to do that can't be done once the main story is finished (like the DLC, for example). Please consider implementing post-game content 🙏

Yeah, Bethesda certainly fixed Fallout 3 with that... Rather than a satisfying conclusion that changed the face of the capital wasteland for the better or worst, it added a series of mediocre battles and a game that never ends until your interest fizzles away.

I truly hate when a game just keeps going after the story concludes. Completely removes any impact the outcome of the main quest had, because more often than not it means that it had no impact at all.

In game DLCs are good. Post campaign DLCs are good. For replayable games, I generally favour in-game DLCs, as content from those (be it narrative or items/systems) can contribute to consequent playthroughs. I am not sure Outer Words is quite as replayable as New Vegas or PoE1&2 to really benefit of it, but as I am readying for my 2nd playthrough - I don't mind. 

I didn't play Broken Steel (vanilla game bored me, so I didn't explore extra content), so can't comment. I generally feel that seperate campaigns need to be really robust to work on their own.