Just remember the theme of the convention everybody: "Keep Seeking First God's Kingdom".
JeezHovah loves line dances and "worldly" music, especially the Vietnam War protest songs. All of this promotes "The Kingdom"* and will surely bring thousands of people into "The Truth".
As others have said, I remember the days when a JW couldn't even have a cup of coffee in a KH on a bitterly cold winter morning field service meeting. "Worldly" music for a wedding? Forget it! "Worldly" music while cleaning or working on a KH? Forget it!
Now WT is endorsing Penetecostal Revivals. I wonder how long before JWs are also 'Holy Rolling" or having Bingo Night? Bake sales?
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* I bet not one JW realizes or cares that no one is out 'preaching for the Kingdom' when they are touring, dancing and listening to concerts instead.