For a very short geeky period when I was about twelve, that's all I listened too. Fortunately the tapes were not designed to be played with such intensity and I found better stuff to listen to...
As for other people actually listening to Kingdom Melodies outside the Hall:
**total facepalm**
Unfortunately, not a question of listened but listen : some of them are still having a real love affair with them. That's literally all they listen to - and if they're not listening to that, they're listening to the latest WT on CD or something in that style. Listening to anything else was a sign of spiritual weakness, so the subject was often avoided in conversation. Heaven forbid if you had to ride in their car with them and thank goodness I never had to go to the assembly with them!
A gathering would never be complete without everyone singing in full voice at least three if not five kingdom songs. Forgetting to bring your songbook to a gathering was also viewed as spiritual weakness!
Even before the new songbook was used at the meeting, several had already memorized many of the songs. I think at least one had memorized at least half of the old songbook which they did while exercising. I wouldn't be surprised if they'd finished the new songbook by now seeing as the new lyrics were so dumbed down.
Oh, and we were all advised to memorize the songs in case one day we found ourselves in prison, we'd have something to do to pass the time.