I would like to recommend having a default playlist called 'Wildcard' that is described (and is configured as) being an utterly unranked random play of all Spotify content available globally.
While current algorithms for optimization are great for finding similar content to what we already like, they are terrible for catalyzing access to new inspiration and variety. It's such a waste of possibility from the available repertoire.
As an example, if I hadn't tripped onto nyckelharpa music via another medium, I would have never had access to it in my search options for finding new engaging content. I would have lacked the vocabulary to seek this choice. This is true for many international instruments across traditions and across lyrical content in other languages. Goodness knows we need more of these connections, musical and otherwise.
Wildcard is the simplest song list/random sort to configure; it's an absence of configuration.
Wildcard can increase the audience for smaller-scale musicians.
As people 'like' songs in Wildcard's random play, and follow musicians and radio stations accordingly, this increases access to new musical genres, styles, languages, and artists - increasing the customer experience value of Spotify - all with performance inventory the Spotify organization already has.
It's simply a way to leverage the media already present, in a very positive catalytic way.