Okay clearly, quite simply put, it's NBC being lazy... no matter how you see it. They obviously have other things on their agenda... being as large a corporation as they are, finding ways to make money, stay a profitable company, and increase ratings. It's obviously not like it was before NBC took over (nor will it likely ever be) at TWC, and to see the LF music be extended in coverage time like this seems inevitable. The people behind the scenes at TWC know that there used to be quarterly and yearly playlists, and they are using that as a justification to not configure new playlists.
The things that I have said here may sound debatable, but honestly, that's how I see it. We all know our ranting and wishing will not solve anything, so the most any of us can do is hope that a new playlist comes about.