they will not fix this as the Wii U lacks the hardware to do on-the-fly (Dolby Digital Live/DTS Connect) conversion of audio for use with SPDIF.
Nintendo also would not settle for encoding multichannel pcm as Pro Logic II (that's what the ps2,GameCube, and Wii do)
the original Xbox had Dolby Digtal Live hardware to take 6 channel PCM and re-encode to AC3 (Dolby Digital) on-the-fly
The 360 and PS3 both do the same also.
(the original Xbox and original 360 had no port but had AV cables that had an SPDIF port on them, the original slim [S Model] does have a port)
http://www.dolby.com/us/en/professional/technology/gaming/dolby-digital-live.html --source for the Dolby Digital Live infomation
the PS2 used Pro Logic II encoding to allow 2 channel PCM over SPDIF (and analog) to have surround sound.
the Wii and GameCube did the same but used analog only as they lacked an SPDIF port.
if the Wii U had an SPDIF port, it would only do 2 channel PCM max (as Nintendo would not pay royalties for using Pro Logic II encoding), which is why SPDIF was left out. (whats weird is that as of so far, a few of Nintendo's first party titles, like NSMB U are stereo only)
the last big reason Nintendo left out SPDIF was that since it can not play DVD's or Blu-Rays, it does not have the need to use the SPDIF port for passthrough of DTS/Dolby Digital soundtracks used on movies.