The Crystal Tower raids saw a generous surge in popularity when SE added Aether Oils to the weekly quest to incentivize people who were working on Anima weapons to populate them. 1800 tomes for running 3 24 mans was a pretty generous offer. Now Aether Oils are down to 350 poetics, and the allure is much diminished.
I expect that SE will eventually add a weekly quest for the Mhachi 24 mans also, probably also tied to the SB relic system.