There is content that is only accessible on dark fantasy mode though. Although it's only two scenes for the same character, it introduces the possibility that, down the line, there may be more content unavailable to people who play on power fantasy because they want to not worry about stat checks. And it's not content that comes from a failed check either, but a scenario that plays out drastically differently depending on certain dialogue choices you've made, two of which, out of three, simply aren't available on power fantasy. In such a case, knowing how to manipulate the stats so that you still don't have to worry about checks while also not being locked out of content would be very helpful, especially since, on dark fantasy, you're pretty much required to give away a captive or two to achieve all the content available without destroying the kingdom.
With things how they are now, and might be in the future, a mod that maximizes things such as treasury, morale, and stats could probably be very helpful, actually, now that it's no longer redundant with locked content being introduced.