There should really be a way to easiliy move a song to annother playlist. Right now you can only copy it and have to then delete it from the source playlist first. Why not have <shift> drag'n'drop move instead of copying like in Windows Explorer and most other programs?
When you want to rearrange your playlists it is twice the work not being able to move songs.
Updated on 2019-09-26
This idea has been submitted one year ago, but unfortunately hasn’t gained enough votes during that time (100 votes/year). In order to keep an overview of the active ideas in this forum, this idea will be closed for now. Note that this does not mean the idea has been declined by Spotify.
Please feel free to re-post this idea if you still feel you want this implemented. With a little change in presentation, maybe this time it will gain the necessary support from the community.
For more info: