That's because DK is the 8GB gorilla in the room.
But really isn't this game supposed to be fully rendered in 3D even though it's played from a side-scrolling perspective? That might be the reason.
And just compare it to a game like NSMB U, which from a technical standpoint is almost no different from the original NSMB on DS with the exception of its shiny coat of HD paint.
On 2/24/13, MB1025 said:
You know I was always wondering why no one ever used the dollar sign for $ony, but then I realized they have no money so it would be pointless.