The argument for a complete blank slate to roleplay onto never really sways me because unlike in a game with real intelligent rule masters, these games are only ever going to be so reactive to your decisions. This has been the direction crpgs have been going since Mass Effect(?), and I can't really complain too much about it, it can create moments of dissonance between your intention and your avatars actions but that comes more down to how well the game is creating scenarios for you to work in.
Yes, an ongoing trend in RPGs was becoming less of an RPG and more of a linear action games, with some light RPG appeals. Definitely I wouldn't accuse Larian games so far of going full-Bioware, though, but that's an odd comparison to make.
It might be a preference, but I feel RPGs work better if we actively, and constantly make decisions about our approach and roleplaying choices. That is why Bioware morality and "choice" was, in my opinion, never compelling. If we get to do only one decision (I am good or I am evil, I am paragon or renegade) then the majority of the game is mostly passive when it comes to roleplaying. Even game with wider spectrum be dull if choices follow clear archetypes - I found Kingmaker incredibely dull as rarely I was challenged to think what my character would do in that situation - just pick line corresponding to my alignment of choice without a worry. Tyranny is another example - great first act, and after it's mostly following the path set out by out initial actions. At least we can go full chaos if we get bored.
So yeah, having my character defined the moment I start the game just isn't very interesting. Having unique alterations on subsequen playthroughts because our race/class/background is great, but not as a main characterisation. Those characters won't be as strong as Geralt or Shepard - on a simple basis of not having the entire game build around them.
Origins will be like BG3 cinematics. Yes, Mass Effect1&2 and Witchers storytelling was enhanced through use of directed cutscenes for conversations, but just slapping camera closer doesn't automatically achieve the same effect. It would take incredible amount of work to create a game with that many well-written and characterised defined PCs.