I think we just have two very different use cases. I’ve used MP3 players and SD cards on smartphones in the past and for me streaming is such an upgrade.
Dicovering new artists or albums would mean having to cull something else from my collection (or upgrade storage, which isn’t really always feasible/practical). Now, it’s as simple as right clicking and adding to a playlist. I can jump from Wu-Tang to The Mountain Goats to that one band that’s coming into town I might want to check out to fucking Crazy Frog if I feel so inclined. Sometimes I want Jack Johnson, sometimes I want Louis Armstrong, sometimes I want The Who.
I don’t think I’ve listened to any of these artists for any particular amount in the past year or so, so why would I have them downloaded? But after listing them I might just go make a somewhat eclectic Spotify playlist.