I have my Sonos:Connect connected to my TV, and one thing I would LOVE to be able to do is play music through the TV and use the TV as a controller. Being able to see what is playing, and use my Roku remote to rate tracks and control playback.
As complete as the Sonos experience feels for me, this is definitely a place where I feel I am missing.
Some of the streaming services has Roku apps, that definitely fills in some of the gap, but not all of them do. Plus this doesnt allow me to modify groups, which still has to be done through the use of a phone or computer.