Plain and simple, it comes down to leadership.
XIV doesn’t have WoW’s budget, but they have a strong leadership group in YoshiP, Ishikawa, Koji, Oda etc etc… and all the while, they train the new folks well and get them involved in the design (Kate taking over for Koji, for example, so seamlessly we didn’t noticed for almost 2 expacs).
The general infrastructure of WoW even has some advantages over XIV. The 1.0 spaghetti code is still much more of a detriment than what WoW has been running on; Blizz did some real good engine and system updates around Cata (and beyond).
While XIV 2.0 was made to have player housing from the outset, I bet Blizz could figure this out given ample time and resources to the project.
If you want to know the process for how ARR and HW were made (and how it continues to this day) part 2 and 3 of the XIV noclip documentary has YoshiP explaining the ins and outs of it.
WoW needs a proper director/producer with vision and dedication to the game, first and foremost, not the MAUs or investors. The latter will reap the benefits of the former, but this needs to be conveyed and proven to them.
This kind of talent, while rare, is not a singularity- YoshiP is impressive but nowhere near the only person who can pull this kind of thing off.
Just my two cents.
ALSO:
re: the update cadence… it’s fine. We got MSQ, a whole new PVP mode, a new alliance raid, new daily quests (battle), new weeklies (crafting/gathering), adventure plates (silly, but fun) and a bunch of other stuff… such as DSR… it was fine patch, and we know we get another dump of content every 4 months.
If people are bored and complaining about it, they likely burned through the content fast, don’t like Crystalline Conflict, no-life’d everything to 90 (this is me) and either don’t care about Savage or Ultimate… or say they do but actually don’t just to complain.
I’m honestly done with the current patch content for the moment. I’ll log in a few times a week to run some old raids for fun and that’s fine. XIV isn’t a job.