Having good voice acting doesn't need to be at the expense of good game play. In fact good voice acting can very much be a sign of good game play, as it shows the studio is dedicated to the production of the game and making it top tier. Are some voice actors expensive compared to others, yes of course. However, look at the list of actors they have in there, none of these folks are 'new' actors turned voice actors. They are all people who have been doing it for a while I believe and do a very good job when they do. There is a reason people remember Mark Hamill's joker, or John de Lancie's Discord... because they do extremely good jobs at them, and they put some of themselves into those characters. I would expect nothing less from them here. Hell even the flops of a game Quantum Conundrum was, I still enjoyed it because John de Lancie was guiding me through it.
Voice Acting and Sound in general can go a long way from making a good game great, and a great game last a life time.
As someone else said, it is all a matter of personal taste, but I for one am glad to see WG Labs spending the effort to do VA well, it gives me hope for the rest of the game.