I can kind of see the logic behind this, but historically main villains have almost never survived the expansions in which they are featured. Even if the Danuser/Afrasiabi drama never happened, I honestly can’t see a universe where the Jailer survived Shadowlands. Garrosh survived MoP just so he could kick off the next expansion, and then got killed in a cutscene during the quest experience. Sargeras got to survive Legion because he’s iconic, but alt-Gul’dan and Kil’jaeden weren’t so lucky. All other major villains were killed off in their respective expansions (unless you’re a N’zoth conspiracy theorist, of course).
It also feels super weird that the entire team sort of resigned themselves to having two expansions relegated to the role of “filler.” I don’t think we’ve ever seen anything like that before in WoW’s history.
I personally think the correct explanation for the Jailer is also the simplest one; the writing team genuinely believes that the best villains for WoW are the ones that are big, bad, and boring.
It genuinely surprised them how much everyone loved Denathrius’s role in Shadowlands, so they had to do last-minute story tweaking to save him. If that sounds familiar, it’s exactly what happened to Bwonsamdi in BFA. He initially wasn’t going to have any role in Shadowlands, but when fans deemed him the best character of the expansion (because he was) that had to change.
And remember who turned out to be the big bad of BFA? N’zoth. Inherently not a bad choice, but they wrote him so poorly. They chose to characterize him as yet another big bad who speaks slowly in a booming voice while insulting us as “mortals.”
But if you want a slice of what we could have gotten, just look at Azshara’s warbringer short. Fish N’zoth oozes with personality. That swindling, mocking, fishy dealmaker type is exactly what everyone loved about Bwonsamdi. We thought we would get that again when N’zoth finally made his move. Instead, he does tentacle stuff to two zones and then dies to a giant laser, and now the writing team can’t bear to reveal whether or not they actually intended that to be the moment of his death in the WoW universe (they might retcon it later due to fan pushback, but this totally was meant to be the way they killed him off).
The “speak slowly and be big” villain archetype is something the writing team genuinely either loves for themselves or believes us to love. Maybe they’re trying to recapture the love the community had for Lich King Arthas and Sargeras. Maybe they simply don’t know how to write anything better and only occasionally strike gold with Bwonsamdi, Azshara, and Denathrius. Maybe all three of those characters are actually written terrible and it’s the voice actors’ input that ultimately saves them.
Regardless, and maybe this is just me being pessimistic, but I believe Zovaal is the way he is because the writers genuinely tried their hardest to make what they thought was a good villain.