In the eyes of many, the Holy Light is considered the energy diametrically opposed to Dark Magic Power, while the force of nature is more inclusive, for death too is a part of nature, and there should be no obvious conflict between the two.
This statement isn't wrong, but it's not entirely correct.
Because many people think that the concept of death in the Undead is the same thing as the death understood by Druids.
In reality, this isn't the case, as death in the eyes of the Undead is eternal, whereas death in the eyes of Druids is a cycle.
Undead: "Ah, I have died, but I have also attained eternal life. I shall exist forever."
Druid: "No, no, that's not allowed. You need to become nourishment for other life forms, die a bit more thoroughly for me!"
Herein lies the contradiction.
Therefore, the force of nature can accommodate death, as long as you're willing to be a part of the cycle, but it can't tolerate Dark Magic Power, as its existence is a disruption of the cycle.