They, unfortunately, estimated their time wrong. They probably believed that they could finish programming it, finalizing it, port it over to America for Translation, mass producing it, and shipping it to retailers quicker.
So yes, this is partly because they added more features and decided to polish the game. Everything is connected in this.
I, for one, am glad that this game was not released (as planned) at the
Wii's launch. That would have been a sad, strange little game.
This, of course, gives me more time to play No More Heroes. NMH ftw!