Voice acting is prohibitively expensive compared to the costs of many other elements of development. This is why it is used very sparingly at present. I would personally much rather they focused on using their budget efficiently by spending it on things that players are likely to make regular use of, as opposed to cutscenes that most will only ever see once.

Now VA for bosses in dungeons is a different issue and one that I could support, though again I would want the devs to focus on making efficient use of that budget. Some VA is great but too much will mean less of other things that likely hold more importance to most players.