There is quite a lot to unpack here and cover. I won’t be responding to all of it.
My point about the palaces being the epitome of Highborne arrogance has to do with what it represents.
Azshara’s palace is the result of her elevating herself above her people. The motivation and inspiration behind such palaces stems from avarice.
The temples of Elune does not represent the same thing. That is selfless devotion of giving thanks to the maker, as is appropriate to do in sacred sites. Elune became a faraway concept in the mind of Azshara and her lackeys when their fondness for the Arcane overshadowed pretty much everything else. It basically became their new God - an act of idolatry.
And I will stand firm on that the Kaldorei are most definitely likely to be monogamous. Even if the RPGs are no longer canon, it is hinted in them that the Kaldorei take companions for life. Tyrande and Malfurion having been together for 10k years and then eventualling marrying (because the end of the long vigil enabled them to do so) reflects a large part of Kaldorei society - how they appreciate the unity of two coming together as one.
The Alliance Player’s Guide: “Night elves do not traditionally marry, but they do take companions for life.”
Marrying is not what is traditional and is what made the union between Malf and Tyr different, but their lifelong companionship as mates is something that permeates their society due to the values and traditions they hold. Let’s also take into consideration that they evolved from Trolls. The Trolls engaged in brutal sacrifices, cannibalism, and probably even inc*st. I wouldn’t be surprised that they practiced polygamy and then the Night Elves learned to appreciate relationships that are much similar to how humans come together IRL. And honestly, the Kaldorei are far more pure and holy of their mindset (Whenever they do not covet power, like Azshara) than Humans in the WoW universe. I dare say they do an even better job at appreciating their kin and understanding love than we as Humans IRL do.
They are a stark contrast to Trolls in terms of culture and traditions.
With that trivial point done with, however, as it’s not really the main subject, I do not believe the Kaldorei, as hinted by the Chronicle books and other sources of lore, did exist for very long before Azshara’s empire tbh. They came around 15k years ago in the timeline? That means that only 2-3k years later, Azshara came about with her empire.
“Around 15,000 years ago a tribe of Dark Trolls unconcerned by the battles for land and power and longing for a peaceful connection to the world…”
"In time, many of the night elves yearned for a different life, drawn to the arcane, they became obsessed with unlocking the Well of Eternity’s secrets. They rigorously studied the fount’s arcane energies becoming learned sorcerers. They harnessed the powers of the arcane lake and constructed wondrous temples and roadways around it. Magic became an inseparable part of life as the night elves reveled in the power at their fingertips. "
I think much of the lore speaks for itself in regards to the fallibility of Elves and their proclivity towards arrogance. Arrogance is also always a latent trait that is still noticeable in them. That is not just the Kaldorei, too. It is the Shal’dorei, Sin’dorei, Quel’dorei, and Ren’dorei. It’s because they are all related and frequently show re-emerging signs of self-asserted superiority to other races, as they deem their allies primitive.
I do not believe it’d make sense at all for the Kaldorei to establish new cities identical to the ones during the empire. The Kaldorei made their mistakes and were humbled by it.
Their practice of Nature (Druids) and Stellar energies (As priestesses and druids of the moon) far better reflect the union between Elune and Malorne, and then by extension, the original will and purpose Elune had for her children.
Honestly, a reiteration of Darnassus or something even more humble than that would be fine and make complete sense.
That is my final take on the matter.