A dual function pull down/toggle button (much like the back and foward buttons on IE) would be an excellent addition, but the idea of creating view schemes to go along with list schemes is pure genius, and for the reasons that Nila stated is additional genius. If MC wants to be your tagging, DB, Player, burner yadda yadda yadda, then this is an integral concept to that goal.
I spend time adding things to Playing Now, go back to my tagging duties, retrieving album art...and each time I have to change the view scheme...and I've done this A LOT! And with my size DB, it's tedious, especially when I have to toggle through the "single song album art" view. Now I like the idea of that particular view existing, say, when I have a mix going and playing now can show you each art file in your list, but a better idea for that function would be similar to how AV2 works, with a thumbnail followed by detailed text of each file (which also offers a very quick view of files that need art). Other than that, I don't really see much use for the "single song album art" view, it's just too space consuming and confusing.