Gordon Freeman is an icon. And a very silent one at that.
There have been a few silent protagonists throughout the years, some very popular too, and Gordon Freeman is just one example of this. Jack from Bioshock is another. Both games were praised for their immersive storytelling, rooted in the lack of cutscenes and this feeling that the player were really being this person.
Personally, I think all that is wrong. Half-Life 2 got boring and Bioshock was a good game, but nowhere near worthy of all the praise it got. In both cases, the storytelling was a weakpoint. These characters show zero emotion, and saying I cared about these two in any real way would be a joke. I couldn't help but see them as retarded muppets, completely incapable of social interaction and with a dead stare in their eyes. Probably some drool hanging from their mouths.
However, it worked in Portal. The character you controlled was a blank slate, who would never see human interaction throughout the game, and thus never get to show the weakness in storytelling that Jack and Gordon showed in their games.
Overall, I much prefer someone who can respond to a situation with words, rather than someone limited to the point and click interface of an FPS for social interaction. Give me vivid characters that I can connect with instead of empty shells (Nathan Drake is a great example), thank you very much.
EDIT: For clarification, I mean protagonists that are not actually responding in any way. Characters that just don't have voice acting but still respond, like in Dragon Age: Origins or Fallout 3 are fine.











