Uh, I had my Wii U hooked up via component/stereo cables, and it output pro logic just fine, which is a type of surround sound.
It's a surround sound that your receiver creates. However, the Wii doesn't feed it a surround sound signal. It feeds it a stereo signal that the receiver turns into surround sound.
Don't get me wrong - there's absolutely nothing wrong with it. However, the native LPCM is going to be a higher quality surround sound experience.
Nothing wrong with it, but the Wii U doesn't support Dolby Pro Logic II, so it doesn't output the appropriate flags in the stereo mix for it to be "true" Dolby Pro Logic. Only certain games in Wii mode will supposedly allow a DPLII mix.
While true, any decent receiver can take ANY Stereo input and output PLII, with or without flags in the mix, and do it very well.
However, I don't think anyone can argue against the fact that the best way to experience surround sound from the Wii U is by having it connected to a receiver via HDMI. --- Gaming is like a pair of boobs - Sony and Microsoft fight over whos boobs look more realistic, while Nintendo is about having fun with them - Walkiethrougie