It's not quite that simple. Another price you pay, is that in any big game (And RPG-s tend to be quite big) there are many more characters in the game, than voice actors available. Oblivion was notorious for everyone basically sounding the same and that was a major reason why many peaople loathed it.
Another big problem is, that voice acting is usually recorded far before a game gets released. When the developer wants to iterate and change things around, they simply can't without arranging another voice acting session.
In conclusion i think proper VA needs both a very good VA director, and many different voice actors (preferably at least one for every major character and enough for minor characters). Otherwise there is no point of doing full VA at all. Games like Oblivion and Deus Ex certainly suffered because of low quality VA, and these were AAA games with enormous budgets. A game like Wasteland 2 has simply no resources for full VA.