The impression I've always had is that Exalted is, assuming you don't deliberately ignore the wider implications of the setting in the name of having a good time (or ignore them IC because your PC has a different view of things), a game where the only "message" is emergent from its established ideas - namely, that power inherently destroys all it touches, peace is meaningless and/or unattainable, and the best that can possibly be done is to procure success and happiness for you and yours while leaving the rest of Creation to rot, then manage to die of old age before your sins come back to haunt you.
Any more positive interpretation requires that you assume one of the prior ruling factions (the Primordials, the Incarnae, the Deliberative, etc.) was right and then work to restore them to greatness, which is essentially that last option I mentioned but with loftier ideological motives.
Them not saying "hey, by the way our section on Terrestrial Breeding has lots of disturbing racial supremacist undertones and creates a mechanical implementation where banning miscegenation and conducting arranged marriage programs to reverse the impact of previous miscegenation results in stronger Dragonbloods" does not mean their writing doesn't say so anyway, if you understand my meaning.
Still, let's lay this all out.
Terrestrial Exalts are a superior race of human, who derive their superiority from the purity of their bloodline. The less foreign blood has entered their family line since their race's founding by Gaea, the more powerful they are. The Realm
[1] actively seeks to preserve this blood purity & maintain their racial hygiene via careful systems of arranged marriages (even to the point of inbreeding), and deals with "Lost Eggs" (Terrestrials which have zero Breeding, and arose due to miscegenation between Terrestrial Exalts and mortals) by offering them The Coin (military service) or The Razor (sterilization to prevent them from birthing/siring any more mixed-blood Terrestrial Exalts).
The Immaculate Faith is predicated on the idea that Terrestrial Exalted are the ultimate life form, the final destination for a human soul before it becomes one with the Elemental Dragons, and that mortals are meant to serve them in the hope their fealty will grant them higher status in the next life.
Terrestrial Exalts might have been intended to reference ideas like the "blood of kings" or the Numenoreans fading away as they intermarried with mortal men, but the issue is that those ideas feed into the favored narratives of ethnic supremacists - that their "race" is better than any other, and under threat of losing its superiority due to an influx of foreign (inferior) blood. The idea that "high breeding" grants you actual superpowers is a direct mythologization of supremacist logic.
The authors had to come up with an in-universe contrivance
[2] to explain the lack of
Lebensborn projects among Terrestrial-led cultures, for Pete's sake.
[1] Hey, there's that culture of Terrestrials you wanted! I mean, they aren't killing off non-Dragonblooded humans, but that doesn't really make them any less predicated on ideals of racial supremacy that happen to be factually accurate because of authorial fiat.
[2] The idea of Dragonblooded women needing several years of recovery time between births, specifically.