While I find the Discovery Weekly (and other editorial features like Genre collections) fantastic personally, I think the thing that keeps me from making Spotify my end-all-be-all music solution is licensing.

There are plenty of songs which I've added to playlists, only to find a year or two later are no longer available due to expired licenses. Some of my favorite artists and labels - Drag City is a big one - aren't available on Spotify at all (usually due to objections to the royalty structure). Many live albums, and more obscure and vintage releases are often nigh-impossible to find, or only have one or two songs from the album: likely those that have been licensed previously for use on TV etc.

Spotify is great, but it will forever be fighting the friction of music licensing and fair monetization.