I'd only see voice acting as being neccesary if you were talking about a game with TONS of dialog like Xenogears was a game that deperately needed it Xenosaga thankfully did have almost exclusivly voiced cutscenes. Zelda games arnt that "talky" though, they dont need to be and thus the visuals can speak for themselves.
I, for one, was glad Link didn't have a voice in soulcalibur (aside for battlecries and grunts), it made him standout and probably one of the coolest personalities in the game.