Quote Originally Posted by wereotter View Post
It's not just "a" Crystal Tower, it's literally the same Crystal Tower as we're seeing in Mor Dhona, transported across worlds and time. You see some of this on the screens and in the data logs in The Twinning. So the story about who is Graha Tia and what is the Crystal Tower is set up to a large part of the story for the expansion.
The story of G'raha Tia was related to the main story, but the MSQ of shadowbringers can almost entirely stand on its own feet without any real understanding of the relation of the Exarch to the crystal tower on the source. The post-Shadowbringers MSQ is a slightly different matter, but even that could be explained away with a few lines of expositional dialogue, instead of wasting hours of each player's time going through the crystal tower raids.

The tower basically serves as a mcguffin that links the source to the first, but it's not integral to the actual storyline, except as far as it was shoehorned in.