That's an absolute statement of human nature which Miyazaki intentionally left vague-he directly said that the story is meant to question human nature, including whether it's kind, selfish, malignant, simplistic, complicated, and so on. Humans in the game range from the Oolacile citizens and darkwraiths being CHAOTIC EEEVILLLL, to Solaire and Laurentius, who are very pleasant, kindhearted people.
I also never said anything about Gwyn 'resisting the course of nature.' That is a viewpoint on the situation that the game makes sure to give some evidence. (regardless over whether it's right or not) I view the forces of the Dark as just as 'unnatural' as the forces of Fire; they are both deviations from the basic state of the setting, which is grey/colorless, twilight/shadow. The very nature of the world before the Flame of Disparity and the very meaning of Disparity is 'difference.' Combine that with the description of the Age of Ancients, "In the Age of Ancients, the world was unformed, shrouded by fog. All there were were archtrees, grey crags, and Everlasting Dragons." This all pretty strongly implies that the world was homogenous, grey and singular until the Flame of Disparity, or 'Flame that is/causes Disparity.' (differentiation) Saying that Gwyn averted the course of nature can be reasonably viewed as true-if it is, though, so does the Dark, because the Dark is by its very nature another differentiation, another presence that existed only after the world became dualistic instead of singular.
Also, I disagree about Linking the Fire improving things in any way. Linking the Fire keeps the Gods in power while the Dark and Abyss still exist and will always exist at least as long as the Fire does (because the very nature of the Fire and the Gods is dualistic and must have a counterpart) and this same situation will always keep repeating-cycles of warfare, an overzealous and oppressive mainstream religion, waves of hollows, and all of the people lost along the way. Ending the Fire and becoming the Dark Lord lets the Chosen Undead become the new ruler of the world (theoretically, at least) which puts him or her in the position to potentially improve society somewhat-if the effects of the Dark on humanity allow for it-for example, the humanity running wild not making everyone murderous maniacs. I note that the Darkwraiths, ghosts and bloated people were not killing each other so much afterwords. This may just be a gameplay mechanic-or the residents of the Dark, amidst the supposed madness, may actually be treating each other humanely-and, potentially, better than they did before. I doubt this; I'm just acknowledging that this is a possibility.
There is also a lot of in-game material that points to the religion that the gods have founded and the society that they have spearheaded as tyrannical and detrimental to humans.The Crestfallen Warriors Dialogue, especially that regarding Anastacia, has parallels with the history of the Christian churches and Rome in Europe. (or at least what people think the history is) The Male Undead Merchant's dialogues also comment a little on how life was back in 'civilized' lands; even the most benign, sane undead are oppressed, similar in a fashion to any sort of so-branded heretic in Europe. The Female Undead Merchant's dialogues also mention how horrible life was before becoming undead and being locked in a sewer. Even her string of curses upon being attacked, while they do not speak for the gods, do not reflect well at best upon how 'benevolent' the gods are.Anastacia's dialogues show her to be quite pious-and self-loathing to such an extreme that seems to think she deserved to have her tongue cut out and feet cut off. Reah's dialogues obviously is a very pious woman-who, by a mission set down from the church who receives its orders from the gods, (suggested to be Lloyd) did indeed go straight off to pillage graves. One in four of them (although with only four, this statistic does not necessarily reflect the actual percentage of clerics as a whole who are like this; on the other hand, there's a reason he's in the game) abandoned the others and later assassinates Reah if he can. I think Reah also parallels Farnese from Berserk, who was high-ranking nobility and basically the leader of the Knight Templars. Farnese later leaves the Church altogether, follows Guts, a demon-slayer who she was originally sent by the Church to kill or imprison (who worships extremely powerful demons that portray themselves as angels) him, and begins training in healing and defensive witchcraft. There are a lot of references to Berserk in Dark Souls; the Manserpents, Capra Demon and basically the Avelyn all appeared in Berserk; Artorias shares a lot of similarities with Guts, including the basic shape of his armor, the connection to a wolf, a greatsword of enormous might, his spinning ariel jump attack; a (at the absolute least debatably) malignant divinity or pantheon that people think is good; and many others that I either missed or am just not going to take the time to put here.
My basic point is that life under the rule of the gods sucks. This is difficult to prove because this takes place in special, remote Lordran, rather than the average world like Astora, Thorolund and so on, and because Miyazaki likes to be so subtle. I think the players are supposed think that the gods and Fire are good, only to discover that they're actually jerkass gods, if not an outright case of God is Evil.. At the absolute least, the gods have done such a poor and irresponsible job that in any other occupation the occupant would have been fired long ago.
Neither ending even can end these cycles because neither addresses what is actually making this setting a crapsack world-people treating other people badly, be they god(ess), dragon, undead, human or beast. The entire conflict is born out of hostility and fear regarding the other. Imagine if both sides just stopped their bickering and got along.
The end does not justify the means; utopia and morality is not achieved through magic and ceremony. Situations are what they are made by, and, thus, the only way to create a kind, benevolent and fair ending is to take actions that are kind and benevolent. The only time peace will ever come to the Fire and Dark is when they reconcile, not when one wins.