You know voiceacting is the most expensive thing in game development, that is why most studios prefer non-verbal solutions.

That's an interesting statement, that I doubt to be even remotely true. If that would be true, than VO would definitely be detrimental. If VO is the most expensive part of BG3, imagine intricate game it could be, if you got rid of it.
Well....to consider it detrimental or not is a subjective opinion I guess. Voice acting done good, can substantially enhance the experience of a game. And considering that Larian ain't an indie developer, voice actors expect to get paid.
So, a professional voice actor can cost around 200-400$/h. Unless your sound designer already has an recording studio, that needs to be booked too. Plus a recording engineer. And a talent director to find the actors you want if it's a big project. And catering etc.
Because of needed retakes etc a company would be wise to allocate one minute recording time per line of dialogue, plus time for editing etc. And BG3 has A LOT of dialogue.
Compare all that to a programmer that needs a computer, a chair and some encouragement from his boss :P well yeah, voice acting is expensive. But the most expensive part...nah. That is without doubt marketing.