I also think there is a more touchy-feely reason for keeping you album off streaming music. With streaming music, all music is counted equal. It’s just as easy for me to stream Adele or Taylor Swift as it is for me to listen to anything else. There’s nothing special about one album over another when everything feels like it’s free. When you buy an album though, that strengthens your bond with that particular album.
The perceived value of music on streaming services is practically non-existent and I don’t blame any artist for withholding their music in an effort to prevent those services from becoming any more popular than they already are.