Any related issue to this has been posted as "implemented". This issue has many followers and the demand is there. You are losing subscribers over this issue.
The Apple watch app from Spotify doesn't allow offline playback or streaming via cell service without the use of a slaved iPhone. This is a crucial feature that seems fairly simple on the surface since every other mobile device has this feature.
Spotify's direct competition (Apple Music) has this figured out and unfortunately is causing faithful and loyal customers to Spotify to walk away because we aren't getting realistic updates on this issue... Instead you are telling folks it is solved.
I have lots of love for you...my suggestion is you give developers an apple watch with cell service and let them figure out the major shortcomings of the current app.