I'm surprised one aspect of a talking Zelda hasn't been brought up: the ability to name Link. It's been a tradition ever sense the very first title, and while plenty of people just name him Link, the ability to name him whatever you want is a major design aspect, and for some people it goes a long way to "linking" the player to Link.
Given the technical limitations (or, should I say, the realistic assets needed to make it work properly), you just can't have voice acting + character naming. They could try to work around it by never mentioning Link by name... but that would get old fast.
While I'm personally not opposed to having voice acting to some extent, I don't want to loss the ability to name Link either.