Why NIS kept Disgaea4 PS3 exclusive?

[Xen]

Galaki said:

Xen said:

It's not their only game. Besides, manifest your interest into a purchase of Disgaea DS. You have one, as I see.

I don't want to play an old game :(

It's the best one in the series still - well, with the omission of 4, haven't played it yet.