Okay, Long Post Here
I'm going to bring my analysis of the situation to the ring, actually, in that I think the Empress ending is one which is full of ambiguity and this isn't necessarily a bad thing. I also think CD_Projekt Red managed to do an excellent job of throwing a lot of subtle visual clues about the situation which means that it's not really the "Right ThingTM" to do and a nice contrast to other games.
One thing the game does with Emperor Emhyr is that he is portrayed as an incredibly ambigious figure throughout. We gain no deep insights into Emhyr's personality, motivations, or goals other than a few brief conversations which the Emperor is deliberately guarded.
I discuss this in my essay and while some people say this might be a flaw in the game, in fact, this is painfully deliberate as we get insights into every single other character. Emperor Emhyr is almost unique by the fact he does
not open up to Geralt but keeps their conversation down to a bare minimum. Book readers have an advantage over previous games players but even then, Emhyr's behavior is questionable because it's so different from previous ones....and similar too.
One thing I've mentioned in other threads is that a lot of the Witcher is basically Deconstructive Fantasy. For those unfamiliar with the concept, it's when you take apart the assumptions of a specific genre and subject them to scrutiny.
Watchmen is the go-too example for this as it takes apart the assumptions of a superhero story and says, "aren't people who put on costumes to beat other people up very weird? Wouldn't people with superpowers be alienated from the rest of humanity? Isn't it kind of horrible the idea of saving the world through one man's will than just the rest of humanity working together?" In the case of the Witcher Saga, the world deconstructs stuff like the Passage of Elves (extinction is not a sad but beautiful thing), race relations (showing what Medieval race relations were really like), and most of all, the CHOSEN ONE storyline.
In
The Wheel of Time, Rand Al'Thor is the Dragon Reborn and while it's no picnic for him, he becomes showered with riches and love interests and eventually becomes ruler of half the world. In the case of Ciri, she is constantly neverendingly on the run because of people who wish to control her for her power and used as a political football wherever she goes. The Witcher 3 is about, essentially, having Ciri deal with all of her enemies so she can finally know a bunch of peace as an adult (or no longer have to worry about people using her as a pawn). With the White Frost destroyed, she's not really someone everyone DESPERATELY needs and most of her enemies are dead or in retreat.
Except for Emhyr who is going to make her Empress! Which is totally a great reward, right?
She's like Aragorn or Arthur, the One True Queen.
Yeah...perhaps not so much.
One area, CPR did well is that they kept to the Deconstructive nature of fantasy. In
Dragon Age: Origins, you have the character of Alistair who is similarly a reluctant king. He doesn't want to be King (you can encourage him to do so), he doesn't particularly like his father (you can encourage him to forgive him), and you have to force him into the role of monarch more or less. About the only people who got something similar to Ciri were those playing nonhuman or mage romances as Alistair had to leave them because, again, as King his life was no longer his own (even then, he chose death over them dying if there wasn't a third option). For a lot of gamers, though, Alistair becoming King was about him stepping up and receiving his reward.
I don't think that's what this is about, though.
Nilfgaard is a kingdom built upon the fact of slavery, conquest, and ruthless expansionism. It's not noticeably worse than, say, many other kingdoms because Sapkowski is as romantic about feudalism as George R.R. Martin. However, that keeps the point that
Kings and Monarchs are assholes. Foltest is the nicest one of them all and he still tried to have Ciri killed as a young girl and got thousands of people killed because he refused to marry Baronness De Lavelette. Ciri is going to be coming Queen of Nilfgaard by ascending to the throne of a place which her father constantly had to engage in miliary conquests to keep ahead of as well as constant acts of murder to avoid assassination.
Furthermore, EMHYR COULDN'T CONTROL NILFGAARD. As much as I hate Emyr, I don't blame him for the Massacre of Cintra as that was his own generals choosing to INVADE THE COUNTRY ON THEIR OWN AND KILL EVERYONE IN THE CAPITAL.
If someone as ruthless, formidable, and bloody-handed as Emhyr wasn't able to do anything but barely keep the reigns of a land like Nilfgaard then what chance does Ciri have? She's an amazing woman but it's not the case of her being weaker than Emhyr but that she's not the kind to exterminate all of her enemies or, if she is, that keeping ahead of them would involve more acts of conquest and suppression of dissent. There's also the fact as Emperor Emhyr isn't treated as a person but as a god. Nilfgaard is not a place where Emhyr has friends or loved ones, everyone acts in a highly ritualized manner which has elevated him to supernatural status. It works for Emhyr because he seems comfortable with being isolated from others but Ciri is going to be surrounded by fawning scyopants and liars the rest of her life. We see the kind of scum which floats upwards toward her with Philippa Eilhart already planning to become Ciri's advisor--which she TELLS GERALT TO HIS FACE WHILE INSULTING HIM.
The ideal ending is, of course, that Ciri masterfully will defeat all of her political enemies. That she'll reform the Empire into one of good. That everything will end up in a Big Happy Ending with the Good QueenTM.
And....that's not really how the Witcher series rolls.