Indeed. I think that because Valhalla's story was so repetitive, it followed the same formula 4 time or more (there's a bad guy inside the fort, do some missions to get some help and then invade) that fighting a strong enemy felt like a chore, it didn't feel rewarding killing a hard enemy
Yep, exactly. You lose sight of the goodies in the grind. It becomes just another special enemy downed, another special item to maybe use for a while... that's the other thing, with so many of them, they can't ALL be amazing... or even usable, depending on how you like to play. But it does yield to this 'burnout' effect, where even if the story is good, you almost stop caring because around that is the other 70% of the game that is pretty much the same things over and over.
But you hit on the flipside of the coin later, too. If the story that these mechanics carry is good... the setting and lore have depth, the characters are interesting, plotlines are engaging, atmosphere is dynamic and nuanced... you can get away with quite a lot on the gameplay side. It's just that to have a game with AAA scale, that requires a lot of original ideas with good communication and execution across a wide range of branches in the team. EVERYBODY has to be working in some way, to prop up the story. At that point, simplicity and repetition make more sense. If the player is incentivized enough by the story, they will of course be more willing to complete simple, repeatable actions to progress the story. It's worth it, and in that scenario the gameplay stays out of the way. It wouldn't work as well to have like 2 hours of hardcore gameplay (or just dicking about) and then get hit with more story. It becomes disjointed. The pacing is screwed... you are held hostage. You can't hope to pack a TON of both in. You're gonna have to put some sheen on that. Because underneath, it won't all fit.
But again... scale becomes a problem. When you try to have a main beat that is literally an epic with more than say... 6 main characters and say twice as many side ones... and then you have side stories intertwining and people on the other end building a massive, fractalized world that there needs to be lore established for.... not many can do it. And nobody does it consistently. It works much better for more traditional story games. A recent example I can give from my experience is Plague Tale: Innocence. That game is really only about one main story with a handful of characters. The levels are linear and relatively small. The whole game is small. But every bit of it is perfectly honed to carry the story, which is, I think, a pretty engaging and unique one. For once, I felt like I wasn't playing through a rehash of story beats I've been seeing in books my whole life. And the gameplay was SO rudimentary... like really easy and basic. There is a simple crafting system... not much else. As you play through the game, it's just doing the 'show' part of the story, and everything is geared towards that. But it works and it doesn't wear you out.
That said, would never scale to a AAA-sized title. But that is to say, the attributes in the game are thoughtfully balanced. A lot of the open world games seem to be at an arms race to be bigger and have more stuff... but they still want to have that grand story progression and convey this living world to you. It leaves so many loose ends to tie up, and at some point it gets channeled down to methods that generally work and can be scaled up quickly. You can't eat your cake and still have cake. There are compromises. The cheaping-out has to happen somewhere or the thing will never get done. Open-world is in a weird state right now. On one hand, I think there has been tons of innovation in graphical tech and visual design. That was something that brought me back, to see and experience these incredible scenes. These worlds are REALLY starting to live and breathe in a more visceral way... no longer is so much suspension of disbelief required to believe you're in the place the game says you are. It looks and feels that way... which opens doors to A WHOLE LOT of opportunities for all sorts of clever story conveyance... maybe even things we haven't seen before.
But in addition to that, these games have shot up in size over the years... pretty much because they can and people seem to like that. They can use traversal and side-stuff to boast larger playtime figures. That's a problem, too... friggin playtime is a bogus concept AFAIC. Yes, a game needs to have sufficient length to really scratch the itch. But that doesn't make that scale that brings playtime in spades inherently better. It introduces complications. You have so many elements in there, things do eventually have to start getting simplified to balance-out. Which then starts to cut into the quality of the experience. And nobody seems to have a working solution... betting some indie out there has it and we'll never know
Well... I guess it works for them, if they get sales. They're massive undertakings... so something must be going right to keep doing them. Forgive me for this, I have no hate for Assassin's Creed... like, at all. Buuut, when it comes to this style of game in general, I think a lot of them get made because the hype marketing works just fine and they can ride on them for a long time if they do halfway decently. But then... to get that hype, they have to always be BIGGER, MORE COMPLEX, ALL OF THE GAME MECHANICS. I sometimes wonder if it's possible to pull off, or if this open-world model will sunset in the next 5-10 years, when people get tired of the cycle and there simply is nothing new to see or do with them. I love open-world games. That's my biggest kick. I just wonder if the way they're done presently can continue to work and produce really gripping titles. You get some SERIOUS gems. There are good, fresh open-world games you can play today. But they all bear similar flaws. They're just better balanced to them, so the player lets it go a little more often.
Sometimes I swear to you, it's simply the aesthetic that makes or breaks them. Many people will be in a world that's cool and interesting to them for a long time, even if everything else is average to mediocre. As long as there's no dealbreaker bug or mechanic. Might be why they stick with gameplay that's easy to understand and generally feels good. It's just safer. Red Dead tried switching-up with some of their mechanics and people just lost it. Personally, I just appreciated the level of integration with the overarching concept for the game.They're uniquely geared to the game, the story, and its pace. It's thoughtful, even if the controls kind of suck

I'd like to see more of that mindset, though maybe all open-worlds shouldn't be quite like RDR2

It's more about the mentality behind how one brings in and distributes mechanics and story. That's what I'm looking at, here.
I mean... when the AC franchise really got its stride, what were people talking about? A fleshed-out, less-explored setting with unique and fun traversal mechanics... maybe things you could do in the game that you couldn't in others. Things like that. Times have changed since then. None of it is new anymore. The experiences you get are kind of just different flavors of similar things. The time to innovate or die is fast approaching, I think. It just feels like there's a big wall to climb over with these things, but they're all just setting up shop at the foot of it.
I'm really rambling now. This is one of those topics that I think could go in a million different directions. Oops!