I think Monster Hunter was always popular.
However it really was held back, by what was possible on a handheld.

People that enjoyed MH games, might have grown tired of the games going nowhere. Because they couldnt, limted by the hardware they where on.
A new MH thats suddenly a level or two above any prior? that seems to be something new and improved? it draws back all those old MH fans that where tired of it being stuck in the mud going nowhere.

Then theres the people that where always on the edge... should I try? maybe they didnt have the platform for it, and long wanted to try it.... now its on their platform and so they go in. The metacritic scores of it being by far the best its ever been, made alot of those people that long wanted to try it, jump in.

Also its taken off, to such a degree, that friends are nudgeing their friends "get monster hunter, and we can go hunt together online".

Its just a perfect storm really.
And a game thats been improved to the degree that people are curious about it and want to try it.

If I were Nintendo in this instance that you paint, they should probably create their own game that challenges what MH brings. CAPCOM hasn't really been supporting them that great, so most fans don't experience their games on Nintendo systems anyways. 

The true test for this series isn't in this game but if CAPCOM does its rehashes as they are known for on the 3ds, will the retention rate of buyers stay with the franchise. People blame Nintendo for taking or keeping their games away from them, but you should really blame CAPCOM, since they were gladly raking in the high profits from what was low cost to make these 3ds games.

Why do people say stuff like this, the MH games on 3ds clearly helped fund CAPCOM transition to HD on 360/PS4 and for them to try risky new things. People quickly forget that most Japanese developers struggled immensely switching over to HD and CAPCOM wasn't immune to this and many of their franchises failed because of high development costs.

Still have my PS2 copy, so I dunno what you're talking about.

I tried MH and its not for me, making the graphics better still wouldn't have gotten my purchase. The grinding that is required in these games and super long monster fights is what will turn most western gamers off in the long run 

All that missed sales from X1 in Japan.

Significantly less grinding in World thanks to Investigations and Melding. Investigations give oodles of mats, and Melding less you combine rare mats for super rare mats.

I am so overjoyed that MH is finally popular in the west.I still remember playing the first MH, it was a real bummer that everyone I knew didn't like it, so I just couldn't talk about it.I have to admit it is somewhat frustrating that now we're getting the best MH to date, and now that MH sells in the west, it is then that I just don't time to play anymore.Anyways I'm just glad people are enjoying the game, hopefully the franchise keeps growing.

"3ds games were irrelevent for MHW's sucess"
Excuse me? Whike it maintained its sales in japan, MH4 is the one that first broke 1 mil in the west.

Aanyway I'm guessing thier western focus paid off a lot.

As of japan... COMEG numbers show that its going to do worse that portable 3rd/4/4G/cross, but by how much we have no idea.
Considering the main cultrual thing of MH being played with local multiplayer... I'd still say 2 mil in japan LTD. Which still is freaking impressive only lagging behind DQ and splatoon, japan's biggest games at the moment

Most western gamers are playing now, having fun and are fighting super long monster fights and are grinding for better weapons and armor.

thats whats going on ^^

Also MH is about the skill. Not the grinding. Its about getting better with every hit, with every step, with every new monster you can feel your improvement.

Monster Hunter is getting the attention it deserves