I'd much rather RPGs had no voice acting whatsoever, even if the decision didn't affect the amount of dialogue & quest content. I like to imagine the NPCs' voices. I can even think of a few ways to handle dialogue in a near photo-realistic, visually detailed gameworld
without it being voiced. But I fear the silent masses expect voiced actors nowadays, and always will, so it's understandable (and not overly disappointing) that developers bow to that. As long as the player character remains silent...
I think you can have fully voiced AND have more quests and dialouge. It's all in WHO you get to do those things. If they spent the money on local talent instead of spending it on hollywood actors they would be able to add more dialouge and more quests and better directions.
I agree that three good voice actors would be a much better use of a game's budget than one recognisable one, but I really don't know enough about the factors involved to say whether or not that's a real consideration for devs. Unless Bethesda are holding back more "big names" for Skyrim, though, they've seemingly followed this course; I highly doubt Max von Sydow cost as much as Stewart, Bean and Stamp combined.