While not really "silent protagonists", I think Bioware and ...what's that other one...oh, Obsidian had the same types of qualities in mind when they decided to make Revan and the Exile "silent". Silent protagonists allow the player to better relate with the PC by being able to put themselves in their shoes without the PC fleshing themselves out with their own dialog. Of course, that point is sort of null with the dialog system in the KotOR games, I suppose, even if you are the one choosing the responses.
I think if, hypothetically, a KotOR III were to be made (which it's not), then having actual, voiced dialog would be a viable decision by the devs, especially after having played games like Mass Effect where cinematic conversations were implemented so well.
"Pick up that can."