I think the reason behind it is the fact that you HAVE to be dark to achieve what Briala does. Words and kindness will get her nowhere in Orlais. And not just because she is an elf. Kindness is irrelevant in Orlais, only the game and how you play it matters. She plays it quite well, and can bring a whole nation to its knee with only eyes and ears of servants who work for nobles.
Given how the ruler of Ferelden basically failed the Dalish with the Dalish Boon (the Hinterlands), that's quite true. Briala took action to help empower her people. As she said, "The elves of Orlais have a future. For the first time in centuries."
Briala ruling towards Gaspard can cause problems unless the Inquisitor is an elf. There is an special epilogue if you are an elf. Your relation with Briala keeps stability.
Which makes me happy, because it offers some hope for the Orlesian elves, and all the elves who are living in the Dales (which Briala apparently now governs as Marquise). Even Lavellan can proudly ask Solas if he's pleased that they helped their people.
The elf Inquisitor is an exception though, the epilogue is different. Indicating the Inquisition and Briala's relation keeps the stability.
Which I'm completely fine with, since the Inquisitor was able to help his people have a real future after centuries of servitude, abuse, murders, and purges.