Changing up what the Shadowlands looks like won't change that it has no preexinsting lore to build on for the final patch.
MoP might have been mostly new stuff, but it also constantly pulled from the well of preexisting lore or teasers. Whether it was the Alliance and Horde setting up camp on the southern shores, Zandalari showing up for 5.2, or the final patch taking us to Orgrimmar to defeat Garrosh.
Shadowlands might have had a better told story or better pacing, and that might have salvaged much of it, but as it stands Zereth Mortis is a completely new location, with no prior buildup outside some of 9.1, where we will defeat a boss that we know barely anything about, to stop his plans that we still don't relly know what are.
That's what I mean when I say there isnt a whole lot to be passionate about. The story doesnt really have much lore to utilize to make the story feel grand or epic like players would usually expect it to. It can be a great patch with wonderful content, but it won't make players passionate about something they have no reason to care about.