When you remove UC and Tel from the equation – which tbh virtually all of the questing content does – it instead sums up to:
Alliance: We are a coalition of many, guided by justice.
Kul Tiras is a human-focused adventure dealing with significant corruption in its ranks that has wrested control away from its rightful rulership, at a vaguely early industrial fantasy tech-level, which hits in the middle of dwarven tanks and marble castles. While politics is an unavoidable facet of things for humans, however, the zones largely push towards the Real Threat – there’s something bigger lurking in the shadows that the politics are really just a distraction from, an otherworldly threat or two that’s beyond mortal comprehension. And even the most frivolous of people, when presented with this threat, will turn their attention towards dealing with it if they have any nobility in their soul at all.
The War Campaign showcases the ingenuity of the gnomes, the reliability of the Wildhammer dwarves, and Shandris is a serviceable if not compelling depiction of someone who stands apart from the CoF races with an incredibly different perspective but respects them. The War Campaign takes pains to highlight the differences of every core race, using Telaamon as a stand-in for the Draenei generally, and is really rare in that it actually brings up the unfathomably long lifespans of the Draenei, Void Elves, and Night Elves as compared to the CoF races and how it affects their perspectives.
There is a strong undercurrent of moral responsibility throughout; sometimes the characters hate doing their duty but they’d never think of abandoning that duty.
Horde: We are brothers in arms, united in face of a world that hates us, ever seeking to better ourselves.
Zandalar is the first in-game depiction of the trolls that does the trolls justice, and it clearly sets up a grand empire long past its heyday but not out of memory. The loa are the best depictions of religion that WoW has ever done by far, and manages to hit the naturist themes the Horde has come to rely on without making them feel primitive; no, it’s quite clear that Zandalar is no one’s inferior, and by extension, so is the Horde. Corruption is also a theme here, but not nearly as much as hubris and neglect; Rastakhan didn’t do anything evil, but he got lazy, and even when he gets prodded into action again, he makes presumptuous actions on behalf of others he really shouldn’t (like pledging the entire family line to Bwonsamdi). This helps underline just how immensely powerful Zandalar really is as an empire, which is why the crowning questline for the region is entirely about political duties – no supernatural threats to distract.
The war campaign gives a complicated portrayal of what it means to be Forsaken in Voss, Zelling, and Nathanos, followed by a complicated portrayal of what it means to be an orc – someone who has followed others into atrocities until you could bear it no longer and turn against that. Tauren are self-sacrificing to a fault. Goblins are presented with both Gallywix and Gazlowe to ponder. Trolls don’t get much emphasis here, but Zandalar as well as the Vol’jin quests more than make up for it.
Blood Elves… exist, but we appear to have collectively decided that Blood Elves exist after Sunwell Plateau and that’s about it.
Honestly, BFA questing is a really, really good introduction to the central themes of WoW if you completely missed WC3 and Vanilla. The Alliance only appears inept when thrown into the grand picture of the metaplot; if anything, from the questing experience, the Alliance feels hypercompetent but not infallible. Similarly, there’s nothing that seems or feels inexcusable about the Horde within questing only – they make the hard decisions they have to to survive. Sylvanas did SOMETHING bad but if you’re new, it’s hard to grasp the magnitude of how bad it is without specifically touching Darkshore content (and even then, really.)