I see what you mean, but I don't really think there's a problem with us having no idea about the Absolute and what it really is. It's a mystery and it's meant to be a mystery. I'm thinking back to Pillars of Eternity; sure you physically SEE Thaos early on, but if I recall correctly, you don't really get any context to know he's significant or the main bad guy until like, act 2. It's not fundamentally different from how we become aware of the Absolute early on but probably aren't going to find out what its deal is until later, most likely at Moonrise tower. I think the real problem is that we lack a conflict to emotionally invest in. The threat of the tadpole really falls flat, since the game does a poor job of selling the threat of it, but at the same time it never really gives us a cathartic moment of releasing the initial threat it set up so we can feel good about exploring further. The narrative still pretends the tadpole is the most important thing when the storytelling and gameplay tell us not to worry about it.
I think that structurally, The Absolute (I actually like the name, by the way. It's firm and to the point, simple in a good way I feel) isn't even meant to be the 'main villain'. Or at least, the absolute ISN'T structurally the main villain whatever the intent of the writers was. It's a mystery to solve, same as the tadpoles. I don't think not having a clear villain is necessary from the beginning, especially since Larian is clearly trying for more of a sandbox approach to encourage exploration. But the story is just unfocused and the parts ultimately don't work together.
And to address your latest post, I would argue that our Tav is very much bland, unremarkable and non-special as an MC. Certainly if you step back and compare them to the rest of the party. Also to bring up your point about the openning being 'Marvel-inspired' I have to disagree with you there. What Larian is doing is writing 101: starting with something especially exciting to ensure you grab the audience's attention. But like everything else Larian does, they cranked it up way too far. Based on what I've seen in the Original Sin games, this is still entirely within their style and to blame Marvel for it is just taking an unnecessary shot.
I agree with parts of what you say but just to be clear, my intention was not to blame Marvel; I really don't think they can take the credit for that kind of writing/dialogue. It's more that that particular 'tone' doesn't really appeal to me. For anyone who has seen The Last Jedi during the opening scene where Poe Dameron is facing off solo in his little ship against a Star Destroyer (or whatever it is, I'm not a Star Wars lore expert), the dialogue is full of wise-cracks and has an OTT comical flavour which I just found a bit immature and not very believable. For whatever reason I found much of the BG dialogue reminiscent of this particular style and it's just not for me. Some people like it, that's fine but as I have said before, it feels different from the overall tone of previous BG games.