It *is* an either-or decision though, albiet not in the way you're thinking. The game's budget is a 0 sum, so if money is diverted into giving 10 (assuming the 4 existing player voices and the playable npcs in early access are all there is) that's going to have to come from somewhere else. I'd rather Larian spend that money on fully voiced player voice acting on new maps, spells, monsters... stuff.
I think you need to learn a little more about budgeting and development process of games. More importantly how budget is distributed to each department. The audio department has nothing to do with the people making maps, spells monsters etc. Not to mention, you are just making a blind assumption since neither of us are actually studio employees. So neither of us can speak intelligently in regards to budget restraints etc. When I see people go on about cost effectiveness and budget etc, that is just their way of adding credence to their personal preference. If you aren't a fan of voice, that is cool we all have our preferences. Just say that, but don't act like you have some insight on the studios budget process, and what the can and can't support lol.