Uuuuhg, damnit, ok. I really really wanted to try to read this entire thread before posting, but I just keep coming up with too much to say. So what I'm going to say now is just my opinions on things. If it feels like I'm calling out or responding to anyone in particular, I'm not, I likely haven't even read what you'd said yet. Anyway…
First off, I cannot agree with the idea that Link cannot be given a voice or complicated dialogue because he serves as the player avatar. My evidence: Master Chief. He is by and large regarded as the almost quintessential gaming "Blank Slate", but he is by no means without a personality. In fact, for anyone who looks past all the pot shots about him being a non-character, there are actually many things you can surmise about John through his interactions with other people, and with Cortana, and more importantly, the differences between those two types of interactions. It paints a picture of a man who is no-nonsense, and who deals with other people in a very regimented line of authority. If you outrank him, you see and hear that in everything he says and does. If he outranks you, you get the same. But Cortana, he is very back and forth with, he is kinda glib with her and in turn responds well to her own sarcastic attitude. He debates the merits of ideas and plans with her, even though he usually defers to her judgement. But unlike any other character ever in any of the games, he does so not in submission to the chain of command, but out of mutual respect. All of this in turn shows you that he is a very detached individual in most cases, but is capable of deep interpersonal relationships. It just takes an incredible amount to get there. Not surprisingly, he only ever shows this sort of attitude to Dr. Halsey, Cortana's creator and real-life counterpart.
So to say that Link can't speak in order to keep him as a player avatar… is completely off the table. I can't think of ever hearing someone say they liked the Halo games or lore, but that 117 needed to "talk less" or that he broke their immersion. If anything, having something of a foothold of personality allowed what would normally have been a regular FPS to have moments of surprising emotional connection.
The second thing I'd like to bring up is that if Link were given real dialogue, and therefor allowed to showcase a healthy range or personality, it could arguably wind up improving the games in other ways. Think about this: how many times have you been playing a Zelda game, and either had to a) sit through a longwinded speech delivered by someone, only to respond with a single line or two that was just you agreeing to do whatever irritating chore the NPC was sending you on, or b) sat through two or more characters talking over you to each other, and then you still just agree to do whatever it is they want you to go do? The correct answer is "literally all the time, every time, because that is what happens." But imagine a scene in which Link is given equal weight in the discussion. Done correctly, it would actually give players more of a sense of immersion and agency, because they'd no longer feel like they were being bandied back and forth like a piece of driftwood on the tides of other character's wishes. It would also keep you invested in the entire discussion, instead of making you get through some of it and then shout "BLA BLA BLA OK OK TRIFORCE GANON SAVE THE THING YEAH I GET IT SHUT UP ALREADY."
The point is that, unlike in the 80's and 90's, we now have a monolithic catalogue of Link's exploits. We've been able to see through our history with him that he is not a blank slate, that he does have a few key defining characteristics to serve as a tentpost for wherever else a story might want to explore. We no longer need him to be a non-entity in order to immerse ourselves, because we get it. We're along for the ride. We know what the daring little lad is about and we're totally on board. Because the dynamic between the audience and Link has changed. Before, it was ourselves we took into the game, and used him to do it. But now, we're here for Link, to be him, to be the daring, courageous, eternally heroic Paragon for the land of Hyrule, and I think audiences are demanding that we be allowed to explore him more as a person (though they may not realize this consciously). Back then, it was graphics and gameplay that had loads of room to evolve, and story and character could take a back seat, no problem. But now, with graphical fidelity approaching the tip of the chevron, it's story and character that have nearly boundless room to grow. And I think by not giving Link more personality, Nintendo is curtailing their ability to deliver that.
