Although becoming a rarer and rarer phenomenon these days, the silent protagonist is certainly one of the foundations upon which all characterization has been built in terms of video games. Like I mentioned in yesterday's posting characters like Mario, Sonic, Mega Man, and many others started off as silent protagonists. This isn't to say they were without personality by any means; after all Mario had his distinctive overalls and moustache, Sonic was a blue hedgehog, Mega Man a pellet shooting robot, and so on. Still, in many of their original outings these characters rarely -- if ever -- talked whether through vocalization or text. This didn't stop any of them from becoming popular and beloved gaming icons though, quite the opposite. And while Sonic and Mega Man do tend to be more talkative these days, the most famous of the lot -- Mario -- is still a fairly tight lipped guy.
So, what is it about the silent protagonist that so often endears us to him or her? Well, I think there are a great number of factors. First and perhaps most obviously, having a protagonist that is fairly blank in terms of attitudes and persona allows a player to easily slip into that character and even pretend to be that character for the duration of the game. After all, video games are great at escapism if nothing else, so why not have that immersion carry over to the character that the player is controlling? There's a certain comfort about the stoic nature of silent characters, a stability of personality tends to carry over from game to game even as the technology allows the character to look more complex and do more complex things.
Of course no where is the idea of a silent protagonist standing in for the player more obvious than in first person RPG's where aside from perhaps character creation itself the game is mostly played through the eyes of your creation. Although there may be dialogue, the choices are often yours to make (if they are somewhat limited in scope, granted) so when a person names the main character after themselves or uses a nickname, it arguably is beneficial in helping cement that link to the fantasy world of the game.
Another point quite similar to the one about immersion is that if a character is silent then they become sort of an icon, something for each player to reflect their own beliefs and personality on to. It's hard to hate a silent character when you're the one in control of their actions; their mistakes are your mistakes, their triumphs are your triumphs and so on. It would take a lot of purposeful design to alienate a silent character from the controlling audience, but far less to endear him or her to them. Because the audience has the broad strokes they are free to fill in the blanks however they please, and things such as the way the character looks and how they handle themselves are used to help mold the way the audience looks at them.
For an example let's use a classic RPG: Chrono Trigger. It's hard to imagine what Chrono Trigger might have been like if the eponymous character would have talked at all, much less to the same degree as any of the other party members or even tertiary characters. Yet, to anyone who has played the game, they know who Chrono is: he's a brave, kindhearted guy who can't turn away from the suffering of others, even if it will technically never affect him. His choices throughout the game reflect his selfless nature and determination to see things through to the end. It doesn't matter that he never speaks; his (and thus the players) actions are more than enough to establish him in the narrative. Indeed, I can only assume that if they had given Chrono a speaking role that it might have resulted in a markedly lessened experience, since if his character were handled poorly or didn't make the right impression then player sympathy would be lost and thus a good deal of the enjoyment taken from the game might have been lost as well.
Now, this doesn't mean that every character should be a mute. After all there are plenty of successful characters out there with a lot of personality that have been made to express it. But even these days when the technology allows for a more in depth use of characterization than ever before it doesn't hurt to look at and consider the roots of the video game character and consider just how much this type of treatment is still used. A recent famous example that I can think of is probably Master Chief from Halo. While he does talk in cutscenes and at various points, whenever he's in player control he mostly is silent. This hasn't stopped him from becoming one of the most enduring characters that exists in Microsoft's library of games. So remember, sometimes it really does turn out that less is more.