All the examples you name either adapt to your tastes, or offer different 'channels' for different genres. I do see the appeal of that. In fact, I love discovery, and human-powered discovery can be amazing.
The thing that doesn't make sense is that it's 1) a single station, and 2) in no way adjusted to the time and tastes of particular locations.
Why would anyone want to listen to that with exactly the kinds of alternatives you name, on top of the fact that a countless amount of more specific stations can be listened to online?
To make a comparison: imagine if Apple released a new Apple TV and then spent a big chunk of time promoting their single, world-wide channel.
Do you know any people who put on the tv and watch whatever comes on nowadays, without switching channels a few times? And if so, do those people do this because they prefer it over, say, Popcorn Time or Netflix, or just because they're used to doing so, and probably pretty old?
Again, releasing such a 24/7 channel in itself is a nice idea. It just seems really odd to put such an emphasis on it.
I think you're underestimating the popularity of radio, too. Pandora and songza are purely radio services, and spotify, google music, and rdio all heavily promote their radio services.