Consistency of layout options is coming up again as I try to describe them on the wiki and still come across many cases of "this works like this, unless you do this," or "in order to do this, you need this particular combination of settings," etc.
Forget about drag-and-drop, that's just icing. The various "Now Playing Panel" components can still be decoupled, which was really the point in the first place So each of these should be separate pieces, able to be moved or enabled/disabled independently:
*Now Playing list: left, right, main panel options (already does this, but it's not obvious that you could separate it from the Now Playing panel or how to do it, as demonstrated by recent question from WimYogya).
*Track Details/Lyrics: one, the other, or both, vertical or in tabs (as now), left or right panel. Option of above or below Now Playing list. No stand-alone artwork tab here.
*Stand-alone artwork: as currently available in left sidebar, with option to move to the right sidebar.
*Player: position options as now. No longer able to have two players (one in sidebar, one at top/bottom) OR (if someone is really invested in having both?) top/bottom player configured/enabled separately from sidebar player.
*Spectrum visualization and wave form: sidebar versions as now - option of right or left sidebar.
*Compact Player/floating window: configured separately from main window components. As-is they don't transfer over precisely anyway. Perhaps just a checklist for which of the components to include in the compact player. Opening the floating window wouldn't close any main window components.
This would massively simplify layout configuration. There wouldn't be any confusing exceptions or exclusions to figure out. You just put each piece where you want it and you're done.