Voice acting has pluses and minuses, and honestly for this game especially, full voice acting would be a bad idea. The money is better spent on the actual game.
And in a multi lingual game you have another huge buget limit.
Also we havent seen how bioware plans to continue to support the game as it grows, while having to include new VA into every content they add in the future.

Its really just not worth the cost in resources for this game. The massive amounts of time and money it would cost, dont equal how much value they would get out of the same money put into game/world/pvp/item/graphics development.