Here, how do they think all this extra stuff up to involve in the plot, and have it all foreshadow later events in the game, when the main mission is to visit eight sacred spots and defeat the being behind an alien invasion? It could have just as easily been as simple as "Go here, fight your way through this dungeon, defeat the guardian, absorb the melody, rinse and repeat," amounting to little more than Super Mario Bros. 3.
But it is. It's as simple as go here, fight your way through this dungeon, go talk to this guy you saw before, go talk to this other guy, go talk to that other guy, fight through this other dungeon, defeat the guardian, etc. There's no branching, or alternate routes through the game, or optional sidequests. There's not even that much foreshadowing to speak of. It's Super Mario Bros. 3 with extra steps.
Consider the Mani Mani statue – sure, you spend some time fighting one person after another as it changes hands, but then it gets busted up and you never find out exactly where it came from or what it was supposed to do.
(I suppose technically you don't have to do everything in the same order every time you play the game – but none of the dialog changes if you visit the shrines out of order, and if you skip one, then you'll be underlevelled for the next dungeon, and probably be overlevelled when you go back to whatever you skipped.)
It seems easy enough to think it up – here's this guy who won't let you through unless you give him something valuable, autographs are valuable, performers give autographs, where would you find a performer, we had that theater earlier in the game, let's put someone in the theater. Boom.