Yeah, I noticed that too since he posts in most of the political topics that I'm interested in, and it kind of seems like a fall-back option for whenever someone accuses him of raging on Nilfgaard.
I honestly think CDPR were able to capture Nilfgaard they way they were actually portrayed in the books, without the patriotic glaze of all the readers who came to unfathomably love a 'free North' (Something that Geralt gives absolutely no fucks about).
As for Nilfgaard being made 'too nice', seriously, what are the alternatives? Look at how Nilfgaard acts in the videogames; it's literally 100% a 16th-century empire in political and social attitude, not too 'good' or too 'evil'. They crack down hard on the peasants that help their enemies, but they show remarkable mercy to those who surrender to their vast ambitions, not unlike the Habsburgs of the Spanish and Holy Roman Empires.
Also, Nilfgaard's 'atrocities' in the books are literally limited to a single account (The Sack of Cintra) by a bleeding-heart Northern spy (Dandelion). People seem to conveniently forget that one city that the Nilfgaardians promised to leave undamaged if they surrendered. Geralt is surprised when he's told that they honoured their promise, remarking how rare it is for a whole nation-state to show such a sense of honour.
As for the Sack of Cintra, why DID everyone start killing themselves and their children, at least according to Dandelion? We don't even know that the defenders weren't just freaking out/overreacting, since Nilfgaard never perpetrated any similar massacres in their other occupied capitals.
They murdered everyone for miles around before destroying Cintra. THAT is why they reacted the way they did.
They also defaced Calanthe's corpse.
As for why the Nilfgaard didn't do it, does it not occur to you it might be because the Nilfgaard LOST the first war? They seemed like they were going to annihilate the North completely and resettle it. They just suffered immeasurable casualties in the process so they had to use more subtle methods the second time. It's why they started stirring up anti-human resentment like Jacques Ailsberg so they could recruit the Squirrels as a weapon against the North.
Divide and conquer.
Nilfgaard isn't honorable. They're just practical. They only started treating people with less harsh measures because the North could fight back.
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I'm a big fan of Nilfgaard and think it's one of the best setting elements in the game but I hate to see it lose it's edge. It's like King Henselt. I ****ing LOVE King Henselt. He's a mean, twisted, evil SOB but he's awesome in his own way right up until Ves. He fights from the front, he's an aggressive military conqueror, he's a raging bigot, and he's a scumbag but he's also a father to his men. He's basically Stannis Baratheon meets King Henry VIII and that is the book version versus child-burning nutso.
Now imagine the Witcher 3 doesn't stupidly throw away such a great character but introduces him as the saintly wise King of the North who Geralt is going to try to help get his daughter back so he can make her Queen and bring happiness to all the various races. I mean, yeah, it's NICER but it's NOT Henselt. I love the Nilfgaard warts and all.
The North is meant to represent a backwards pastoral existence in a transitional state. Basically, the North is halfway between Nilfgaard and Skellige. Skellige is what the North used to be with its quirky traditions, manly values, and rape/pillage mentality. The North has become less honorable and more scummy as they've developed but they haven't made any of the other progresses Nilfgaard has either.
They don't, however, commit genocide or practice slavery or commit organized war crimes on a massive scale. The North is a place where you might get rape and murder and banditry but you don't just go into a place and kill everyone then resettle it. Maybe sometimes with the racism but the Nilfgaard fully intended to exterminate every man, woman, and child in Cintra until they lost at Sodden Hill. There's no need to be patriotic because the North is a craphole but they managed to stagger the giant.
So Nilfgaard turned to more subtle means. They fostered terrorism, fanned the flames of racial hatred, and did their best to divide the North against itself. Just as we see with W2: AOK. They haven't given up on the wholesale conquest of the North but maybe they're not going to try and ERADCIATE all of its people this time because they managed to hold down the Fort.
It's wonderful, really. Ruthless, efficient, cold, and calculating. They're the best AND WORST elements of the Roman Empire with a 16th century coat of paint.