In BOTW 2, completely changes Link and gives him more dialogue when it releases sometime in early 2023.
Link is the protagonist of every Legend of Zelda game in some form. Though the specific character and his background differs from title to title and depending on which of the three timelines each game is a part of, he's mostly the same across the series. This is because he endlessly reincarnates from the original Link of Skyward Sword, due to a curse laid upon him and Zelda by Demise. Despite being a mostly simple character, Link's backstory is surprisingly complex, and is the center of the three timelines. There are three main versions of him: the Link that was sent back in time by Zelda after the end of Ocarina of Time (which started Legend of Zelda's split timelines); an alternate version of him in the downfall timeline that was defeated by Ganon at the end of OoT; and a cartoonish iteration that has no relation to either in the Adult timeline.
Although the original overarching reason for Link's silence can be attributed to the fact that Legend of Zelda started in an era where most RPGs had silent protagonists, it was never known why Link stayed that way when so many other games left the trope behind. The reason why Link rarely if ever spoke wasn't revealed until Breath of the Wild, and even then it was only present in the Japanese version of the game. It states that Link chooses not to speak due to feeling that he must present a strong, silent facade, and reveals Link's true feelings for Mipha in BOTW. This could be an indication that he will gain dialogue in future games like BOTW 2, and may even have choices like he did in Skyward Sword.
Pros Of Link Remaining A Silent Protagonist In Legend of Zelda
Perhaps the biggest advantage to Link remaining a silent protagonist is that it aids roleplay. Without dialogue, players are free to imprint whatever words they want onto his actions, which is always fun. Players can imagine Link as the valorous hero he's portrayed as, a reluctant one who just wants to go to bed, or a spiteful brute who swears like a sailor. Especially in Breath of the Wild, where players are free to do most anything they please, Link's lack of dialogue makes him a blank slate they can personalize as they see fit. This in turn also aids immersion and serves to make them feel like they truly are in a Zelda game and fighting Ganon or Ganondorf.
Another positive is that the lack of dialogue makes Link more consistent across the Legend of Zelda series. If he had dialogue, his speech patterns may end up being different from game to game, especially given the three separate timelines. This might create more of a separation between the different versions of Link, which isn't necessarily a bad thing, but could still make his character and the series as a whole feel less cohesive, and the three games already have vastly different themes across the timelines that serve to separate them. Link acts as a constant that helps tie them all together, which his lack of dialogue helps with.
Cons Of Link Remaining A Silent Protagonist In Legend of Zelda
Drawbacks to Link remaining a silent protagonist in Legend of Zelda include a lack of characterization and character development. Throughout his many journeys in the games of the Legend of Zelda timeline, Link faces countless challenges and interacts with many diverse characters that should lead to changes in his character, but since he never speaks, players don't get to see it. Zelda undergoes significant character development in Breath of the Wild with her struggles to awaken her power and her breakdown during the Great Calamity, despite having very few appearances. Link's lack of dialogue robs players of similar moments, and serves to make him boring and flat.
Another disadvantage is the many missed opportunities Link not speaking in Legend of Zelda creates. He could have the best lines in the series, and create epic moments or give heartfelt speeches if he were allowed dialogue. A good example of this is when Princess Zelda quotes him in BOTW, in a memory where they're both riding horses: "Be sure to take the time to soothe your mount. That's the only way it will know how you truly feel." This line greatly enhances the scene, and would have even more so if Link had said it directly. Dialogue like this while saving Zelda or during final battles with Ganon could create the best moments in Legend of Zelda, and the world of gaming in general, so it's a shame that Link's silence is depriving the series of them.
Link Should Speak In Future Legend of Zelda Games
Overall, Link being a silent protagonist in Legend of Zelda has more downsides than upsides. There's little reason for him not to speak in future titles, so hopefully Link will have some dialogue in BOTW 2, or wherever Zelda goes after it. Even if he only had small lines while still retaining his strong, silent attitude, it would be better than nothing. Given the reason for Link not speaking revealed in BOTW, there's a lot of potential in the series for Link learning to overcome these feelings BOTW 2, which could be a great way to finally give Zelda's fated hero dialogue.
One of the biggest problems with Link speaking in Legend of Zelda could be the sudden shift from being a silent protagonist. After so long of Link having no voice, it may seem strange for him to suddenly have dialogue. BOTW has more voice acting than the rest of the series, so if Link does speak in BOTW 2, he may have a voice as well, which could be even more jarring. Despite the problems it could present, however, Link's dialogue could be Zelda BOTW 2's best feature, so Legend of Zelda should put its potential to good use.