I don't argue against online, in fact I am all for it, but the reality is that with an online infrastructure and even the most rudimentary form of comunication, the annoyance increases exponentially.
It's just a part of online interaction.
Miiverse could be potentially amazing for Nintendoland, but so far it seems more like a dressed up message board and FAQ system.
If they manage to incorporate Miiverse as more than that. To make it the center for stuff like ghost data, challenges (asynchronous like the rival challenges in Forza 4) user created content etc, it could be huge. Could.
Personally I don't see why Nintendoland or NSMBM should be singled out for not having online MP when even games like Rayman Origins and now Legends won't have symultaneous online MP.
It's all about the designers intention, and if Miiverse is indeed as powerfull a tool as it could be, then the online integration of Nintendoland should be another showcase on what this platform can do for asynchronous online modes.