I think the focus of the new songs is emotional manipulation. An idea can get into your brain easier when accompanied by music. The push for practicing the songs is about more manipulation and control. Songs like "Life Of A Pioneer" and "Listen, Obey and Be Blessed" have terrible lyrics designed to brainwash. I think they may have also found that many of the new songs aren't very easy to sing along to and actually take quite a bit of practice to sound good.
I also have a theory that by having some songs that you either have to print out or download to a device they are trying to encourage meeting preparation. If you don't study and note which songs are going to be played you'll be stuck standing there with no song to sing and everyone will know you didn't study.