can we bring back the streamable music player from the 360 into the one?

Since Spotify came to the Xbox ecosystem and Microsoft decided to not continue with the Groove app I think it may be difficult but can always use the uservoice to send ideas https://xboxideas.uservoice.com/

We have spotify basically the same thing

There are quite a few apps, that allow you to stream music and play in the background. Groove will do from your OneDrive and others will allow you to steam from a media server on your network as well. These will play in the background so you can continue
to play your games while music plays.

Copying to the hard disk though isn't really supported.

Hey Manly Sundew,

Thank you for reaching out. You are more than welcomed to submit this suggestion on our
Xbox Ideas page. I'm pretty sure you will find others that would like a nice feature like that to be brought back and maybe even improved upon.

I haven't tried cloud-syncing local music yet but I think the two situations are very similar. Here's what happens with me: Any cloud music is automatically synced to the phone as streamable. If there's already a (previously downloaded) local copy (of
a song), I now have two copies, one streamable and one local. Same thing happens if I have a streamable copy and then sync (the same item) to the phone using the Windows Phone 8 app. In this case a local copy gets created in addition to the existing streamable
copy.

To remove the duplicate, I delete the local copy (use the tap-hold menu on the local copy on the phone), then download the streamable copy.

I hope this makes sense. I'll try and clarify, if it doesn't.