It's grim, sure, but nowhere near the 'bloodiest and cruelest regime imaginable'. Going down the list of good factions:
The morality of the Empire of Man is grey at worst, and Chaos et al. are unambiguously a civilization-ending force that exists only to destroy.
Dwarfs are memed as "le book of grudges", sure. But their enemies are the fascist rats, goblins, and Orks. On that note, Skaven have been memed into woobies by the fandom when their actual behavior is more akin to this passage from the Swords of Lankhmar, which inspired them:
What the Mouser had learned during the council session had been, simply yet horribly, the all-over plan for the grand assault on Lankhmar Above, which was to take place a half-hour before this very midnight: detailed information about the disposition of pike companies, crossbow detachments, dagger groups, poison-weapon brigades, incendiaries, lone assassins, child-killers, panic-rats, stink-rats, genital-snappers and breast-biters and other berserkers, setters of man-traps such as trip-cords and needle-sharp caltrops and strangling nooses, artillery brigades which would carry up piecemeal larger weapons to be assembled above ground, until his brain could no longer hold all the data.
Bretonnia is an interesting case. It is a medieval European society, or a pastiche of one, so it is highly oppressive for those not born into the 'right' station. But the Knights genuinely believe the chivalry stuff and they are blessed by the Lady.
Bretonnia is not GOT; it's Prince Valiant.
I will admit to know only a little about High Elves and Wood Elves, but their biggest problem are the arrogance and the fact that the Wood Elves are overprotective of nature.