"Artist" would be a disaster waiting to happen IMO. A lot of us have multiple performers listed there, and it almost never matches across multiple tracks, even for an album.
EDIT: Don't know if it belongs here or in a dedicated thread, but it seems related. Being able to update "Date Added" in bulk - with a selection menu that lists all the different ones used across the selected files - is very, very nice.
My one small improvement request is to add "Now" as one of the selections as a convenience shortcut to manually typing the current date and time.