In an attempt to be more constructive, let's start categorizing the kinds of changes involved in "modernizing" MH.
Minor changes and stuff that's already done or in progress:
-Update lobby/co-op system to allow drop in/drop out. Totally fine, I want it too.
-Streamline crafting: Already happening with material changes in X
-Streamline trading/farming: Again, in progress with in 4/X with the way the caravan works
-Streamline mission prep: Items sets already exist. Equipment sets exist.
-Streamlining food buffs: Already done in X
-Streamlining usable items: Some have already been consolidated after 3
-Enhanced movement, climbing on monsters: People bring this up all the fucking time because they don't know 4 exists
Bigger changes:
-Removing separate areas: I'm personally against this, but it might be possible to do well. 4 already has fewer, bigger areas. I suppose you'd extend that trend and still have some sort of bottleneck/transition area between the new "zones."
-Emphasize "tracking" monsters? This would be reversing course, game already makes it trivially easy to find where the monster is
-No more needing to find/chase the monster? Directly contradicts the above but people ask for this too sometimes
-Simplify controls: Would probably mean reducing the size of weapons' movesets and vastly simplifying usable items
Huge overhauls/why even call it MH at this point:
-Open world
-No missions/specific hunts
-Cinematic story
-No animation priority
-Removing gathering/crafting
Which of these do you people actually want? What have I missed?
I don't understand why making it an open world means "why even call it MH." To me that would be one of the things they'd logically be trying to work into the formula and it's not something I see as totally incompatible. I don't even like open world games but it's not like I can't imagine how they could fit together.
Changing the mission structure would need to be done carefully but would go hand-in-hand with it being "open world." You'd be dropped into one big world that contains all the biomes and you pick up "quests" "more organically" / by finding stuff in the world. I see this as meaning quests to hunt specific monsters or, more importantly, find specific things would be gone. In their stead you'd just be able to wander around and do whatever.
I don't think you'd remove crafting. That's all the rage in virtually very western open world title. If anything, I think it'd be expanded to the point of being annoying and accompany it with RPG lite attributes since why the hell not.
When you look at your idea list through the lens of how the game works today, it doesn't make as much sense, sure. But I imagine tracking monsters through a big open world might be different (again, I don't think I would particularly like this change, but you could see how a focus shift would work).
Most importantly, I don't think Horizon / Witcher / Far Cry really approximate the series all that well holistically. They each do certain things that are clearly inspired by / improve on some of the MH formula (and other things much worse), but I don't think their designers are really designing in that vein intentionally. I think Capcom could do a better job.