Yes, and well said re: "fantasy worldbuilding in general", because it 100% is a generalized fantasy (and to a lesser extent SF in general) issue.
I think what we're seeing here is essentially Metzen "assuming direct control" (to quote ME2).
I don't think Metzen finds Taelia to be an interesting character, nor her parentage to be a particularly interesting plot thread. Faerin, despite some people's weird hate-boners about her, is a character with a ton more going on, a far more interesting, developed and distinctive visual design, and a character who has ties into likely future content, perhaps even post-Worldsoul-saga stuff, if they save the Arathi Empire for after that (which I think they will, for the most part).