Also Banjo Tooie was just as long so I dunno my guess they put too much effort into story and gameplay
You say that like it's a bad thing.
I hated Banjo Tooie for the amount of backtracking it involved, you constantly had to be going in between worlds to achieve a single jiggy compared to the first game where you only to go back to a world once (Defeat the polar bear with the running shoes that you get in the next world).
Oh, and since nobody mentioned the PS4 yet
I was waiting for any news on the Vita, instead I got a console I won't even bother with.