Wild Hunt/ Aen Elle were just not explained in more detail... thats the main issue. there is a lot of background info about whats happening and why they are after Ciri (both Avallach and Eredin) but game never actually links these up for players, but leaves it for speculation.
Ciri explicitly says why Eredin is after her in the Isle of the Mists. When he wants to abduct your daughter, use her to start an invasion of your world, and potentially kill her in the process, his motivations aren't really that important IMO.
I want more than just their intentions, that was pretty well established from the get go, and frankly not that interesting to me. I wanted to understand Eredin as a person/character, what makes him tick, his management style in leading the Wild Hunt etc,. I wanted to know more about the other Wild Hunt members, their background stories, what they think of their leader and why they follow him so loyally. I wanted to know all of this in relation to Geralt and Ciri, because this is the primary focus for W3.
I get that we might want to see what makes him tick, but why would Geralt? In the context of the story, discovering this would be very difficult (I have advocated previously that this could have been done with a Ciri Flashback mission to Tir na Lia at the end of "Through Time and Space," describing the events that transpired in "The Lady of the Lake") but as far as understanding what makes him tick now, I don't think the protagonists really care under the circumstances by the time we get to the game.