Oh, people have asked. It just is that JRiver hasn't shown interest in changing what is there. To be fair, discussions usually turn into requests for all sorts of stuff, and no consensus on what is wanted. So why change if there is no consensus?
More generally the topic of providing the ability to edit the layout comes up.
I don't know how easy it would be to add or change the layout. I'm sure it wouldn't be hard for JRiver to hard code changes. But then, consensus. Providing the ability to edit the layout, harder. In that thread I link to, it was said that skins can't change the Playing Now layout. But I haven't even looked at that.