MSQ

[Jojoya]

Tower relates directly to later content, so thats not "filler". When that became mandatory, I understood the reasoning.

When Crystal Tower was originally added to the game, it was very much just optional filler content. I ignored it as it didn't impact the rest of the game for me.

It was only when SE later decided to make it part of the main story that it became mandatory and I was finally forced to do it. If it had been intended to be part of the main story all along (which it wasn't, YoshiP has said as much), it would have been mandatory from its introduction.