The shield remote does use Bluetooth I believe, I haven't dug into its internals though.
I kinda imagine that a "real solution" would involve some kind of Android environment, though. Your solution works, if the user has not opted into the youtube/spotify/netflix ecosystem. If they have, it's not a real solution.
I care about my youtube account -- I pay for it, in fact. The recommendation engine is extremely good if you curate it, and I've curated it a ton. YouTube is a beast for knowledge/learning center. Spotify has a really good and extensive music library which makes "not pirating" a real option.
At the end of the day, you need a good UI that implements the features of those services. No third party is working full-time to implement these in open source, and they'd likely shut down if they did. So relying on the upstream apps somehow makes sense.