Preface
The silent protagonist appears in quite a lot of games, they don't speak
I'm not here to say the silent protagonist is bad per se, in fact, you'll see quite a few examples where the silent protagonist may be quite appropriate or compliment a character's personality.
Projecting yourself into the character
This is quite a common argument for how silent characters are a good idea and, there is some merit to it. For example, in games such as Minecraft, Skyrim or Animal Crossing since it is quite appropriate to have a silent character as the main character is essentially the player's projection into the game world. Most of such games are sandboxes where you aren't really limited to what the story requires you to do. In fact in games such as Minecraft, you make your own story. As well as that, the creatures (called 'Mobs') in the game don't really speak in human language so it would make sense for the player to be silent and have no personality.But for a game with a clear story, and defined characters, the silent character probably wouldn't do too much for the story other than be an empty shell for the player. For the most part. Perhaps if you could choose your own path, it would be better but even then I think that having a character commenting on the player's responses to certain bits of dialogue would be a nice touch. I will get on to the latter later.
Gordon freeman from Half life is silent, I think this was far more suitable in the first than the second game as there weren't many characters other than Eli (later retconned into half life 2), Isaac Kliner (ditto), the G-Man (who only speaks in the ending of the game) and a whole set of nondescript scientists and guards scattered randomly throughout the game's environments. The 2nd game had a far more narrative structure. Here, Freeman's silent role isn't as effective since there were actual scenes with characters talking, making him feel more like a spectator rather than someone who is directly involved with these conversations. Thankfully in the recently released game Half life: Alyx, you can actually play as one of the non-silent main characters of Half life 2, Alyx Vance, who is my personal favourite (as well as the G-Man). Albeit, I haven't played this game but it seems like a pretty promising one. I think that the fact that she talks can give the player a way of putting themselves into another character's shoes whilst at the same time feeling like they are playing alongside Vance.
In Persona 2 Innocent sin, Tatsuya (the main protagonist) is a silent character and that suits him because people in the game often get the impression that he is cool, and hence why one of the main characters has unrequited feelings for him. Sometimes he does talk, but only when he is yelling with other characters, sort of blending what he says with them. However with Eternal punishment, when Maya is the lead, she doesn't seem as good as a silent character since she is more bubblier than Tatsuya. Although her dialogue responses are well-choreographed to her personality, it is virtually impossible to know whether or not she likes certain characters. Sometimes silent characters may speak to other people but the player doesn't know what they are saying, which I think can be confusing sometimes since the player would need to rely on other characters explicitly saying the things the protagonist said to them in order to know.
There are some games where the character is silent, but they may have dialogue choices which wouldn't necessarily be what the player themselves would say; I don't really think that that's a bad thing.
Non-silent characters
There is a good case to be made of characters being made into very entertaining people to play as rather than a projection of the player.
There are games that the main character isn't silent, a good example is Terraingma, the main character (Ark) is not silent and he has a clear personality. In the beginning of the game he is quite a troublemaker but he matures into the story as he learns more about the world he is trying to save. He does quite a few quirky things throughout the story. One interesting aspect of the game is that if you choose a dialogue option that Ark doesn't agree with, he will mention the option but then state his true opinion. For example, when a child asks him "Do you like soccer?", if you say yes, Ark will, for whatever reason, think that it means sucking and mentions "I like soccer. I like lollipops", perhaps implying that he may not know what football is. Funnily enough, if you say no Ark will admit that he has no idea what it is - and even spell the word wrong. Even though you don't really have too much choice, it's still interesting to see how your character reacts to a choice that conflicted their opinion.
Sometimes an approach of a semi-silent protagonist can come into play, for example in games like Pokémon mystery dungeon the main character is mostly silent and the player can see their internal thoughts. Same thing is done in Persona 5 where the main character can think some thoughts like what he may think of a place or what his priorities may be, although a cat character, that appears later on, takes over this role, and I think it's quite stupid if you ask me since I would be pretty annoyed if I was told to go to bed by a stupid cat.
The protagonist of Persona 1, 2, 5 and Shin Megami Tensei: Strange journey have voiced lines in battle. Although they are mostly silent, they yell lines in battle, for example, when they attack. The voice acting in Persona 2: Eternal punishment is hit or miss - Maya sounded better in Innocent Sin than she was, in Eternal punishment. In fact, some of the acting in there is hilariously terrible (even with someone as good as Amanda Winn-Lee).
Another example of this can be found surprisingly with Mario and Luigi, although they do not say any in-game dialogue, they do have voiced one-liners or that gibberish Italian they speak. Luigi is especially interesting as he has a more defined personality than Mario, since he is more timid than his brother.
Conclusion
I don't think silent characters are bad, they are quite suitable for games. But I sometimes feel like it is just a cheap way to include a character in a plot or just make an excuse for the player to be involved. You may as well as make a person made out of clay or a robot rather than wasting loads of time designing concept art. Funny thing is, the Disney movie "Wreck It Ralph" the main character in one of the arcade games "Hero's duty" is a robot with a screen. Most silent protagonists may as well as be that character.Anyway that's about it for my philosophy on the silent character.
If you want to save the world from Convid-19, please wash your hands, don't go outside (unless you need to) and play one of my games.
That's all from me!