Kirk was "one of the guys" in STXI, on equal footing with Sulu, Uhura, McCoy and the rest. As a stowaway cadet, he didn't command anyone.
As much as I enjoyed the film, and Chris Pine's performance as Kirk, I'm not sure he'll be a convincing authority figure in Star Trek XII.
I completely agree with you. To me, Pine just doesn't have the presence that Shatner did, and something has been lost in the character. Can you picture Pine's Kirk giving a dramatic speech about the nature of freedom and self-determination (as in "The Apple" or "Mirror, Mirror" or "Where No Man Has Gone Before"), strategizing over chess with Mr. Spock, or quoting famous poets (as in "How Sharper than a Serpent's Tooth"). In TOS, Kirk seemed like an intelligent, well-read, deep-thinking leader, a portrayal helped by Shatner's Shakespearean training. Pine just doesn't have that presence for me - I can see glimpses of it, but if that sense of command isn't evidence strongly in the next movie, I think the audience that were fans of the original series and films will disengage, which would be really unfortunate!