Its pretty obvious that the reason all of the trials this expansion are linked to the MSQ is because they didn't want to have to make assets post for Endwalker's post MSQ, and a separate storyline like Werlyt or Four Lords.
Hell just looking at the Tataru questline they keep advertising as content for Endwalker, its all just been recycled assets and locations.

Honestly it just makes Endwalker feel so small