Possibly because of all the coverage they gave it last year or it could be NA is aiming for a mid 2016 release?
I do agree, it seems a foolish oversight given, this game could feed off the positive shooter vibes and multiplayer community that Splatoon has generously opened up to them on the Wii U. Especially given the lack of online multiplayer support that will curse Star Fox Zero thanks to its rushed development.
But then again, NoA despite making a few entertaining internet videos does act like idiots in terms of scheduling or getting games that could do well out. I should just be glad we are getting Fatal Frame 5 and Xenoblade X this year.