Right now, Tiamat in the anime has nothing more than super strong destructive monster that wants to destroy humanity. I do think the things about how she's handicapping herself and so on would add more to her and make her a better character. You don't really ger much beyond Gil's Beast expo, when people are probably wondering why Tiamat is a Beast in the first place.

If this is added later then fine, but rn I can see why people don't feel like Tiamat has more than just being a final boss cause plot, per anime only.