Wii U will not support any disc-based movie playback
While I understand where they're coming from, I also feel this is a mistake. One of the appeals of the Xbox 360 and the PlayStation 3 have been their ability to function as entertainment centers that do more than just play games. Nintendo already did a system that just plays games, and we all know how that turned out. Sure, I still use my Wii—to watch Netflix.
We don't know what kind of streaming options the Wii U will have, but there's nothing they can offer at this point that the other systems don't already do (and do well).
Lately I feel like the early Wii U news has been all about what the system won't do:
They better show us some real working features soon, because I'm quickly losing my enthusiasm for this thing.
Come on Nintendo, get a clue! If the homebrew community can hack together a DVD player for the Wii, it can't require much of your energy to the same. :/
Like you mentioned, one of the perks of the various systems out there is the "all-in-one" aspect to media access. I think that limiting their system that way will alienate people and limit how the hardware is used.