The DS/3DS are the market leading platforms for Japan.

Monster Hunter is the biggest (second biggest?) franchise in Japan.

The 3DS can run adequete enough graphics to now handle Monster Hunter whereas the DS could not.

Why shouldn't Monster Hunter 3/4 be on 3DS is a better question. PSP was lucky to have it for a few years only because the DS couldn't run the engine.

Monster Hunter is 3rd or 4th; Pokemon and Mario are the clear two biggest franchises in Japan; Monster Hunter and Dragon Quest battle for 3rd.

Shorter answer: F SONY!

Real answer.

Monster Hunter PSP was a port to the basically dead portable system of a experimental game that got cult buzz and blew up into phenomenon that made the PSP a viable platform besides a media device.

They saw the Wii blew up into a major force and move MH3 to that to see how it works. They got a very good result but it wasn't MH Portable numbers. Hence with the 3DS they did a updated port of MH3 in MH3G and got a much better response, the Wii U port of 3G is just something they are doing to once again test the market. The PS3 ports of the PSP games did ok, they are probably testing the waters of the Wii U and have Nintendo's word of assisting in releasing the game outside of Japan.

MH4 is the positive they had from working on the MH3G port for the 3DS and the acknowledgement that the 3DS is the undisputed king of portables in Japan, their primary target audience.

I don't know, but I like to believe that the DS had strong third-party support.

It did, most western developers pretty much stay away from portables aside from some family and licensed titles but it received a strong support up until the end of its life cycle from Japan, when a number of studios started moving titles over to the PSP to get at the massive Monster Hunter audience there and to be able to use old PS2 tools and techniques that they couldn't use on the DS nor wouldn't were out of date on the PS3.

I think this will be the next 3ds game I will be getting!

I'm confused, they said that Monster Hunter needs to be multi platform, but Monster Hunter 4 being an exclusive to the 3DS is best. That's a contradiction and made the statement "Needs to be multi platform" false.

No it isn't: clearly, in context, he means one hardware *vendor*, not one platform, i.e. PSP or 3DS or U or whatever.

Nintendo is the top dog in Japan for hardware.

Monster Hunter is the big new third party franchise.

These two getting together is about as surprising as the best looking girl at a party leaving with the richest, most charismatic guy in the room.

The only reason Sony probably even got MH on PSP in the first place was because the DS couldn't run a 3D engine on that scale adequately. Now that the 3DS can, buh-bye Sony.