The Wii didn't include a DVD playback channel, presumably due to licensing costs. It is possible the Wii U won't either.
The Wii U, iirc, has an optical disk sensor that is like Bluray, and is presumably compatible hardware-wise. It is NOT Buray compatible due to licensing costs.
What if Nintendo offered for purchase DVD and DVD/Bluray playback channels (or simply plugins that integrate into the disk channel), which cover licensing costs and enable the playback of DVDs (and Blurays, depending on version)? Microsoft did something like this with the original XBox, where it won't play DVDs unless the DVd remote receiver was plugged into one of the ports.
You can use the tablet controller's screen for movie controls (or the Wii remote or Pro Controller, but you have to memorize the function of each button). Nintendo possibly could also sell a media playback remote (ideally bluetooth, or it could use a tiny USB dongle and can activate playback functionality like the old Xbox remote did).
Thoughts? I would like it if I only needed one device connected to my tv.