Idea - when you click edit playlists, you should be able to simply just click and hold down on a playlist, then drag it up or down to change the ordering of your playlists. This fits the style of Spotify since this is how you rearrange songs in a playlist. It would be an easy integration and is not tacky at all. It simply would be a positive edition that would benefit those who do not actively use Spotify on an a pc. Please upvote this idea for Spotify to consider :)
Updated on 2019-03-07
Hey and thanks for your contribution!
A similar idea has also been suggested here
Add your vote and comments in support there please : )