For me, the ability to portray character is the single most important element of participation in roleplaying games. First person speech is essential and I value the ability to do a distinctive character voice very highly. This applies to both players and GMs.
I suspect I would fail at Doug McCrae's table but perhaps pass at S'mon's.If Bob's not interested in doing the talky bits, he can play the strong silent type. It only hurts my enjoyment if he insists on playing the party Face and says "I Bluff the guard", when most or all of the other players could have done much better. I once had a guy like that at my table and it was terrible.
I like characters - especially PCs - to be clearly drawn. For me, that doesn't have to mean first person speech - that varies at my table, depending on player, mood, stakes, etc - but I like a player's action declarations for his/her PC to reveal the character as a character.
And as a GM I try to present situations which permit this - so little "generic dungeoneering" (where PCs might all have different voices but tend to declare actions from the same perhaps somewhat narrow suite of possibilities) and more "scene framing".
I do agree with S'mon that "I bluff the guard" is underdone as an action declaration. There's not enough there to adjudicate consequences, especially consequences of failure.