Is multiplayer crippling Mario 3D World's level design?

[Pavolink]

JWeinCom said:

Pavolink said:
From what I have seen, single player will be boring. Levels looks very easy.
One of the E3 levels were a 6-? and it hasn't any challenge.

In 3D Land the main quest was fairly easy, but once you beat it there was a more challenging 8 worlds.  This allowed for newer Mario fans to feel like they beat the game, and gave more experienced players a better challenge. Could be the same thing here.

Sadly, Nintendo believes that the difficulty must be unlocked as a reward for the pain of being bored. Happened with SS Hero Mode and with OoT3D Master Quest.