First I'd say change is always a nice thing to me. To know that they try something new gives a game the feel they're doing it because they think is good, not just to appeal audiences. So I think they should always try something new.
I believe the silent hero thing to be just useless. It doesn't add anything to the game. It may be a clever TRY to let people immedesimate with him, but is it really useful? When you play you decide what to do, but this has little to nothing to do with dialogues. In games whithout NPCs, the hero never talks, even if he's able to! Think of any shooter game or action games like Tomb Raider. In most games the character only talks in cutscenes and this also happens in RPGs, like Final Fantasy! When you talk to people they just answer and you don't get to hear the question because if you're searching for some temple it's obvious that the question is "where is that temple?" But then when the story needs to progress, they talk and do whatever they have to.
So it is absolutely ok for Link to not talk in gameplay, but if he HAS to talk it is silly that they make other characters say stuff for him. Also in the endings he doesn't even say like "It is finally over..." he just stands there with a smile on his face, maybe holding the Triforce over his head.
With the coming of new technologies they put new features in games, like 3d graphics, online games, voice acting...
The silent hero just seem to be something they didn't evolved while they could, a stupid inheritance from the 2d era. It also happened in other games, but most time they then changed. An example in GTAIII, the first 3D title in the series, where the main character was silent. That's basically a game where you can do whatever you whant, so maybe they thought it was a good idea, but they changed it with the next title, Vice City, and improved the plot a lot! They proved that having an appealing main character is better than having a blank one. They also made fun of it in San Andreas, by making CJ call "mute" the main character from GTAIII, that had a cameo there.
But even in GTAIII it was better than Zelda, because in there people give him missions and he's like a silent ruthless killer that do his job without questioning, so it actually added something to the character, and you never get to know if he can talk or not, he just never have to. In Zelda it is poorly done because some times other people actually talk for Link, repeating his question. So they basically include Link's sentence in the game but don't let him say it, like they're not allowed to.
In conclusion, Link talking may be an improvement. It may also be nothing special, but having him silent takes away many possibilities to improve the plot. If they keep him silent, they'd better make it better!