Honestly, I think Monster Hunter could be a great success in the west (as it's starting to be or maybe already is) but it just presents itself so badly.
When I first played it, I hated it. I later recommended it to a friend who likes grindy games and said he wanted a large time sink for summer. I told him I didnt like it but I thought he might. Well, he didn't like it either cause it took way too long to get to the point, and fighting monsters, at first, feels so clumsy.
Later on, though, he got into it after he forced himself to learn it, and started to like it a lot. He taught me the fasttrack way to learn the game and get a feel for it, and, pretty soon, I was hooked as well. Unlike most people, I don't think they need to change the formula for it to appeal to the west (although they may need to because franchise fatigue, but that is another topic), they just need to figure out how to present the game, and teach itself better.
People in the west LOVE crafting games and arena style grindfests about developing skills. Crafting is a huge part of Skyrim, Fallout, Far Cry, etc... Arena style grindfests take many forms in very popular games like Overwatch, Mortal Kombat, and League/Dota 2. They got the beautiful formula in their hands, it just isn't appealing in the way it communicates to players in the west.
Its carries heavy sins like throwing way too much info at the beginning, and giving very long detailed explanations in logs or tutorials. They need to change all of that or wait as it slowly emerges into mainstream, as people learn it and share with their friends, like it is right now, IMO.