It seems NIS could use all the extra money they could possibly get and Disgaea is one of their older IP that they could milk from the niche market.

The graphics is cartoonish so scalling it down a bit if they have to won't be noticiable to most people. They could at least port it to the Xbox360.

They could fold altogether before Disgaea4 make it to the West if they continue to make negative money.

Maybe there studio isnt geared for 360, if there short on money, buying in dev kits, hiring new tech programmers and extending the legnth of the project coul dbe far to costly.

If they already have xbox tech, maybe they just got a marketing deal with sony japan

Surely, they could have a "small talk" with MS and they'll give them some money.

NIS games mostly are niche and it would be sad if they folded.

It was developed using the PhyreEngine. It's a free to use engine developed by Sony that helps developers create cheap games withpretty good production values. It's also a reason why the PS3 seems to get a lot of random exclusive JRPG games from Japan. Disgae 3 wasnot developed using the PhyreEngine, so that could mean that Disgae 4 was developed with a similar or lower budget, despite looking much better.

Because the X360 can't handle the Graphixs and all the date would not fit on a DVD...=p..

Just kidding ofcourse...Anyway why does X360 get all those niche exclusives in Japan?  That are so called deals :).  And how much would it going to sell anyway on X360..

What about Yakuza? Why is that an exclusive? For the same reason?

Because NIS don't make Games that the "BROCORE" Buys.

Doubt it, its probably more because its content. The Yakuza series is only extremely popular in Japan so it makes sense to bring to the PS3 especially as the prequels were all for PS2, the developer probably thought the game would sell a negligible amount outside Japan so why bother wasting the extra money on bringing it to the 360 only to see no return or merely breaking even?

As for the Wii... well... third-parties have never made love to the wii so nothing new there. Though I have to admit I think this would have been a smash hit, especially with all the mini game that could take advantage of the wii's controller.

It's probably related to the engine and the install base. Yakuza 3, 4 and The End (maybe?) were developed using the Marvel V - Engine, which is a fairly new engine that was built with the PS3 in mind and focuses on facial expressions, body animation and environment detail. Team CS1 have had plenty of experience with the engine on the PS3 and I'm sure the effort to change it's basic structure to fit on the 360 probably isn't worth it. 

The userbase is also on the PS3, which for a niche game, is probably pretty important. A game like Metal Gear or Final Fantasy are aimed at larger audiences and so it is reasonable to believe that those audiences are worth going after, Yakuza is aimed at a specific audience and most of it's in Japan, a country were the 360 doesn't do very well. 

Sony could also be throwing some money at SEGA, which is possible when you consider how popular the franchise is in Japan.

You forgot Ru Ga Gotoku Kenzan the first in the seires on PS3.