Just wanted to chime in that I'm also hoping for this feature to be added.
I just recently switched from Winamp to Wacup and I regularly create playlists that I'm re-ordering manually.
From the left pane in the ML, it seems I'm only able to nudge the playlist up or down one position, but it's a but finicky and tedious with dozens of playlists.
If I use the main Playlist window, it seems Wacup wants to add the entire playlist to another playlist when we drag-and-drop. Cool feature but I'd rather be able to reposition the lists.
Hope this can be considered :-)