Shadowbringer was the 4th chapter of the story. Dawntrail is the first chapter of a new one so of course it's not going to deliver any big story beat just yet.

If you want to compare dawntrail with something, compare it with arr up to operation archon. It wasn't a great story either and was an extremely cliche good versus evil story until hydaelyn and the ascians were recontextualized in shadowbringers.

You can't reach the heights of stories like shadowbringers and endwalker without doing a whole lot of setup first.