I think it's nice to be able to stream music, since it is quite convenient and (as previously mentioned 80 times) takes up no space, as opposed to vast libraries of music (be it in digital or physical form).
HOWEVER, streaming is absolutely useless if you can't access the internet, and because of that, I will never wholly switch to/use it.
I also enjoy owning physical copies of the music I like, since it:
- Supports the artist.
- Cannot simply be deleted like digital music can. This eliminates the need for re-purchase if your computer becomes unusable, etc.
- Is a physical representation of my tastes in music. I like being able to see (and show off! ) my CDs to friends/family/whoever.
- Cds, vinyl, cassettes, what-have-you, etc etc. can all be used to decorate your home, or fill and empty space in your home (with a nice CD rack, or milk crate of vinyl, for example).
- Every modern vehicle (or at least, the vast majority) have CD players in them, and I hate listening to the radio. I never drive without my music blaring.
All in all, I think owning physical and/or digital copies of music is entirely worth it. Physical copies are a good way to permanently keep your music, and digital copies are excellent for travelling/exercise and the like. In my opinion, streaming just isn't accessible enough (at least, for me) to use, since it relies on a (reliable) internet connection, takes up bandwidth (which the world is running out of!) and means I have to be attached to my computer/smartphone/tablet whenever I feel the need to listen to something.