I agree with an earlier poster that these threads would be a lot easier for discussion if they were posited in a more neutral manner, for example a general discussion about the tone instead of asking what is wrong with it. Also, while I did appreciate the attempts at explanation in the video, I found myself inadvertently groaning when it basically mentioned the decline of darkness in DA games after DAO, as I find DA2 a much darker game than either DAO and DAI.
For the actual tone of DAI, I actually found it to be about as dark DAO, if one can actually really measure such things. For me, personally, what makes a game dark and mature is not the amount of blood and graphic violence in the game, but rather the themes explored in the game and how much it tries to challenge and raise questions on those themes. As DAI never really challenges anything, it at times prompts discussions about faith but even kept them, again my opinion, on a really simple and almost meaningless level. This isn't a bash against the game, it was what it was intended to be, and I felt DAO was essentially the same with all the problems having really clear choices where often one option was clearly the moral choice. Also neither game really had that mundanity of evil that you got in DA2, if that makes any sense. Somehow the evil forces in both DAO and DAI were too epic and grand, again I am struggling for the correct word here, for it to really feel dark for me.
I, however, must repeat that this isn't meant as a knock against DAO or DAI, because it isn't what those games strove to be. As stories, both DAO and DAI were epic high fantasy hero's journeys, where the hero overcomes the initial setback to overcome the overwhelming forces arrayed against them. Such narratives are rarely truly dark due to the story elements involved.
I think the better question would be that has the tone of Thedas turned brighter in DAI, which is something I would argue against as the world itself is as dark as ever.