Ome thing I haven't seen that often was that this was the intention of the makers of these spells, but that humans are so predisposed to darkness that it would require genuine effort and betterment (in a sense, self-mastery on a scale very few people are capable of) to use them in this way. Essentially, that the spells may have been intended to be beneficial, but were accidentally created in such a way that 99% of humans would be unable to cast correctly, instead falling into the trap of using them for darkness.

Especially since the spells obviously become weaker when used with less hatred, the obvious assumption is that they were designed to be fueled by hatred and not that mustering the kind of disposition they were intended for is much, much harder than using them with dark intentions.