First, check out this article on endings in video games. tl;dr: Dude thinks that open-world games should let you down gently at the end. They should provide some aftercare. He wants to be able to go back and see how you’ve changed the world, see how the quest givers are faring, maybe pick up some grateful plaudits.
But then what happened?
My overall response: no you don’t, dude. You think you want that, but it’d be a shit-ton of work to provide, and you’d be bored of it in ten minutes.
Now, there is something unsatisfying about having to save the world, then never getting to explore what happens afterwards. Fallout 3 and Fallout NV are like this: you do a huge thing and then you’re just told what happened later in a slideshow. And half the time this isn’t even very well thought out. (E.g. in my ending of Fallout NV, I have a frigging army of upgraded robots, but I’m told that the neighboring suburb has become even more lawless.)
But really, to get what this guy wants, you’d have to add multiple hours of content (because who knows what part of the open world the player wants to check up on), and almost by definition, what you’re adding won’t be game-like. The big bad got impaled on something; you killed all his lieutenants earlier; there’s not going to be much to do. NPCs are not actually people; during the main plot they got a little simulacrum of being real because they had problems you could solve. It’s not at all easy to make them seem real when the plot is over. “Thank you, Champion of Cyrodiil, things really are better now!” is not really going to be a compelling interaction for long.
This isn’t to say the game can’t let you down gently. I think the later Arkham games are good at this. You can wander around for many more hours doing all the side quests, and finding Riddler trophies. Or you can spend another hundred hours polishing your skills on the combat maps.
The game I just finished, Bayonetta, has a nice approach, I think. You don’t get a lot of “what happened next”. But you do get an explicit denouement scene that brings back the major characters (and offers an easy fight), then a credits sequence that includes a couple more fights, and then an extended dance scene. So you move from some emotional closure, to some low-key interaction (sprinkling the credits with fights is a brilliant idea), to just sitting back and enjoying the dance. It’s like stretching after strenuous exercise, it calms you down and makes you feel good.
The thing that most bothers me about the article is that it doesn’t seem to recognize that the plot’s ending is not the game’s ending. You may read a novel straight through and then put it back on the shelf, but games don’t generally work that way. If you liked the game, finishing the plot may just be the start of your adventure. You play it again, just for fun or to experience different approaches or to challenge yourself on a higher difficulty setting. The real ending is the point where beating up one more thug, or finding one more space durian for the helpless peasant, suddenly strikes you as boring rather than fun.
Besides, it’s a rare game where the actual plot ending is really the high point of the game. I’ve said several times that the best part of Bethesda games is the first 10 levels– the part where everything is new and scary, you’re half-bewildered by all the quests available, and a single stimpak/health potion is a rewarding find. Most game endings are variants on “fight some dude with a lot of hit points”, and often you only use a small subset of the skills you’ve learned. (E.g. many a stealth game offers no opportunity to use stealth during the last boss fight.) If the game explored some darker or more nuanced ideas, that was probably in earlier sections. So while the last fight should be cathartic, it’s a hard ask.
Of course, there are a few games that completely upend our expectations. My go-to example is Fable 3: you have the final boss fight, murderate your evil brother, and become queen… and then find out that you’re facing an even larger problem, the one your brother failed to solve, plus all the promises you made to secure allies along the way now come due. It’s a ballsy move– far more than (say) Fallout NV.
Finally, though it’s true that the devs could say “what happened” for each of the 153 side quests, I’m not sure the article author realizes that an author can always add More Story; the art is knowing when to stop. As Neil Gaiman remarked, in real life people’s stories don’t end until they’re dead. You can’t really ask of a piece of art to let you keep asking “what happened next” indefinitely. At some point the character dies, or the author dies, or you die. If you want more story, get the season pass. Or just learn to appreciate closure, the artistic technique where author and audience agree to leave things be for a time.