Nope, I completely disagree. Her and the Forsaken's story didn't reach any kind of thematic conclusion in Wrath - she confronted Arthas and failed, not out of a flaw of her character but simply not being strong enough in a 1v1 DBZ fight, with Putress' actions ensuring that the Forsaken never actually got a shot at what was their entire goal up to that point. The narrative role of Arthas' past victims raised into undeath was passed over to the Knights of the Ebon Blade, a less developed pastiche of the Forsaken, whereas actually killing Arthas was handed to Generic Human Paladin #4. It was a stroke of unusual genius on Blizzard's part going into Cataclysm not only to acknowledge all of that but to make it the core of her and the Forsaken's story that they got gypped out of their (un)life's purpose,but to make these questions essential. Now what do they do, why still exist and what is their self-image if not victims of Arthas out to get him? Rather than burying this the way they did other huge societal changes, they made answering these questions the entire point of Cataclysm, starting with Sylvanas's short story, which is equally as direct in tackling exactly these 'what now?' style questions. Edge of Night both sets up why Sylvanas doesn't just off herself - she does, and also why she should continue bothering with a people who up until now were an instrument to achieve her goal - she has no choice, otherwise she'd burn in hell. A stable society that has a reason to coexist and won't just collapse at the slightest outside pressure aids both her and them.
This is what we see in Cataclysm - the Forsaken ditch most of the self-pity and their conception of undeath as all negative and themselves as being played out, existing only to take revenge on Arthas to instead reclaim aspects of their identity. The Lordaeronian patriotism that BTS pretends was a Calia innovation and was purely nostalgic stems from here and was much more interesting there. The Forsaken form a conception of themselves as an extant people with a historical claim to their land and who mean to continue existing in it, with undeath becoming a transhumanist state that they view as superior to being alive and who mean to inhabit the world long-term. This isn't some subtle point - it's explicit text with quests titled as ambiguously as
The New Forsaken or
Lordaeron. As far as WoW storytelling goes, it's a fairly complex story of her and them moving on from a failure they'd tied too much of their wishes and also how digging themselves out of a hole and self-pity and making a positive self-conception of themselves doesn't make them better for the world. The Cataclysm Forsaken feel much better about themselves and are a lot happier, they're also more complex given the whole new aspect necromancy brings over, but they're also much worse for everyone around them. Ditto you can't have moments of villain to villain antagonism like Sylvanas and Garrosh's clash or Sylvanas refusing for entirely practical reasons to join in his offensive because it'd mean the end of her and her kingdom and purposefully declining to expand past the historical borders of Lordaeron.
The two major differences with Shadowlands Sylvanas compared to BFA is that she's obviously just a lackey, which the narrative claims reduces her accountability and that we actually see her own mental process while she commits acts - hell, she'll even get a book from her view. In BFA we never got any insight into why she did anything and she never had an emotional reaction to anything going on except that bit with Saurfang I mentioned. It's about how the character is presented.
Arthas was on the box of TFT and the story culminates with what happens to him while otherwise rotating around attempts on the fallout of his actions. He had two campaigns and while I agree that the RTSes in general lay the foundation and the first two don't feature him, WC1 was extremely arch and most people haven't even bothered looking up WC2 hence why there's an alarming amount of people who think the Horde started with Thrall.