I'm not sure why this is so difficult for people to understand.
The option to kill Leliana was a fun bonus in the context of DA:O as a standalone game.
5 years later, we are at DA:I. The writers have determined that incorporating the character of Leliana into the story makes for a more intriguing story for this game and probably the overall franchise. The Keep still tracks all the rest of your previously made choices; if they remove one or a few choices like the Leliana one from the Keep in order to make a better stand alone game, I am always going to be for it. I would even be fine without any Keep at all. I seem to be one of those rare Dragon Age fans who don't give a **** about choices carrying over between the games. What I do care about is choices having significant consequences within the game I am playing (DA2 kind of dropped the ball here, especially considering the possibilities the time jumps allowed for). Bioware can make a Dragon Age game using any "save state" or start point they want. I just want them to make the best game possible each time in terms of reactive role-playing. In fact, I think incorporating previous games' save states is more often than not a limiting factor in reactive role-playing, and can make for a watered down choice/consequence system. It cuts down on how many branching narrative options the devs can feasibly create in the new game and how significant the content can be in the different paths.
Point is: She obviously wasn't "resurrected" in the narrative of the games. She was never killed in the first place in the context of DA:I, and that's the game we're about to play. We can accept this and have fun with the new story, or we can rage on the internet and stay stuck in DA:O. Mark my words: when we get to Dragon Age 10, they aren't going to be able to create a fun game if the players demand it responds to the optional narrative decisions of adopting a nug in DA:I and becoming king of Thedas and abolishing magic in Dragon age 7.