The Roon technology will gradually migrate towards the cloud over time, since that’s where everything is going to end up. It’s not a huge architectural leap to imagine running the Roon “core” in the cloud, with remotes and endpoints in various locations.
The short answer to “why not now” is that hardware, internet speeds and pricing models, and content delivery technologies just aren’t there yet to make a great user experience. @danny goes into more detail on that topic here.
We are not pointed in the direction of becoming a reference tool and when designing product, we sometimes haveto remind ourselves that “Roon is not a music encyclopedia”. What we mean by this is: Roon is focused on a great browsing and listening experience in context of a set of playable content, not becoming allmusic.com.
Getting content from where it is to where you are is one of the most challenging “plumbing” problems in this space, but we intend to solve it. Remote endpoints and offline mode are a possible solution, but not the only way.
It could also take a Tidal stream and provide a Roon UI. (not sure how technically possible this would be!)
This we will do. Your instincts are good on the difficulty level–it’s not a simple thing to pull off 
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