The big ones I am thinking of: Doom, Wolfenstein, Half-Life, Bioshock, and Dead Space - None of those have the main character speaking.
You're right. You don't talk in any of those (except maybe Bioshock: don't you talk at the very VERY beginning, kinda reminiscing (spelling) about the past?), but most of them do something that breaks the sense of immersion that Half Life gives.
Doom: Has that face looking at you the entire time, pretty much guarenteeing the fact that you'll 'snap outta it' when you look at your health. Same with Wolfenstein (right? I haven't ever played it, TBH).
Bioshock: Like I said earlier, I'm not sure he doesn't talk. Also, though, you see your arms a LOT in the game. Still a great game for immersion, it's hurt by the fact that you see the characters arms when he uses most of the weapons.
I know nothing at all of Dead Space. Sorry.
So, sure, you're right. In those games, the protagonist never speaks.
BUT, how many of those games are so driven by the character's choices as Half Life? Now, I haven't played Dead Space so I may be completely off here, but essentially...those other games focus more on shooting and scary than Half Life, which is more on puzzles and choice.
Eh, just my two cents at 3.30 in the morning. Half of this probably didn't make sense. Sorry, and goodnight.