Larry Norman had a song entitled "Why Should The Devil Have All The Good Music". The WT probably wrote off "Christendom's" music as the Devil's music, but they've been trending lately to more Hillsong style choruses, I believe*.
I wonder what's driving the trend? WT music has been described as dirge-like, historically, but so what? The WT always had tight control over the sheep; it wasn't like they were allowed to go to other churches where the more upbeat songs made the WT versions sound like crap. So why bother with the change? If it's dull, but all you've ever known, you're hardly going to be champing at the bit for something else.
*From comments posted on this board