I'm not opposed to changes to the MH formula.
When MH4's announcement trailer was first shown off, I was cautiously optimistic: the larger environments, environmental destruction stuff, climbing, mounting, etc., all seemed like neat additions to the formula that could bring in more people. I was a bit disappointed that MH4U didn't fully flesh that stuff out, but I loved 4U enough that I really didn't care in the end, it felt like a fresh enough update over 3.
I'm not feeling World because A) Capcom's track record of modernizing franchises is very hit or miss, and this feels like a far more direct play in that direction B) the exact ways they highlighted those changes, for the most part, feel antithetical to what I love about the series. I don't mind more environmental destruction or even necessarily the seamless zone changes in theory (though I do worry about how that will be pulled off), but they lead off with stuff like stealth (which is not what I care about in MH at all, since I see it as a pure combat series where you kill or run past anything you don't want to fight anyway) and detective vision (again, I don't see MH as a "hunting" game in the slightest; that aspect is preparation in town, not being a stereotypical mystic tracker with all of the mystique stripped away and replaced with glowy bits). I don't especially care for the design of the new monster (it looks far too plain for my tastes, outside of the inflatable sac). I'm concerned about open world because I never got the sense that MH really wanted to be open world at all, that was something that people projected onto the series to rationalize this modern gaming series deliberately choosing segmented areas.