The optical audio port or S/PDIF is kind of outdated and the data bandwidth just reach the limit... current and future HDMI versions are more than enough to carry more bandwidth and future proof for new audio standard... the optical audio port got no future.
Same old Microsoft! Same mistakes! Oh, and as backwards compatibility goes, It does not play all the Xbox 360 and original Xbox games!! Only the ones the Xbox One plays! And I don't know if they will ever grow that list!