It's not difficult to do voice-acting right (dialogue is a whole other discussion). You only two things:
1) A director who prevents overacting and gets the tone of the piece right. About 80% of AAA studios fairly consistently manage this. Close to 100% when we're talking AAA CRPGs - Larian however do not have a good track record.
2) To get the VA done in an appropriate environment, which usually means an actual studio.
That's really it. They didn't do that here. I wouldn't have cared, because this is an announcement for announcement (repeat ad nauseam), but I was told it was "useful info" so I paid attention to it, and the info I'm deriving is that, at least in this case, they did the two things you can do wrong with voice-acting - i.e. they went with wild overacting, and with poor sound quality from an inappropriate environment. And if I can hear that, on my TV speakers, and not being particularly sharp at that kind of thing, you can guarantee a whole lot more people would pick up on it in an actual game, where there might be countless hours of speech.
If this was some small indie studio with their first game or something, well, yeah, okay, maybe they don't have the money to deal with it. But this is Larian, who sold millions of copies of their last two games, and have multiple dev studios in multiple countries as a result, and are dealing with a licence that stands to make them $$$.
Hopefully they just did this because it's an announcement for an announcement and I only even noticed because I got pointed at it.