Local storage (which is what I think you mean, unless no stream service runs from HDD or no user stores music on an SSD) isn't necessarily better quality, since lossless music downloads are very rare. Also, you're ignoring the fact that buying every song one plays is much more expensive than simply paying $9/month.
You forgot to include paying $0.99/song as a hard disk negative.
Two more possible trade-offs:
- Does the average person know how to transfer their music collection to a new computer?
- Paying for songs a la carte requires thinking about what to buy and deciding if it's worth your money. Streaming reduces that friction.
Having moved to streaming, I can't really imagine going back to storing songs. If I had a really great stereo or headphones, maybe then I'd reconsider. But streaming is just so much more convenient.
+ Huge catalogue on-demand
- Lower quality
- Latency, dropped streams
- Monthly subscription
- Artists get next to nothing
- Player lock-in
Hard disk:
+ Zero latency
+ Highest quality
+ Artists get everything
+ Any player
- Device storage limitations
- Heavy file transfers
I never understood why streaming caught on to begin with.