My point (I guess I didn't make clear enough) is that we never got to see that in TOS, and since STXI introduces a much younger and less mature Kirk, this is something we can probably look forward to in the near future. That is to say, both as a person and as Captain, Kirk has alot of maturing to do; it'll be interesting to see him go from "Talented Young Upstart" to "I remember reading about your adventures in grade school!"
But he's already Captain Kirk. In TOS we found out parts of his past a little at a time. In XI, we got it all in two hours. And he's still the same person at the end as he was at the beginning. (Well, not the VERY beginning since he was just an infant but you know what I mean.)
The trials he went through didn't change him at all. He just got more power to go along with it and most of that was handed to him by Pike (getting him into the academy without applying, being named first officer when he was a stowaway, etc.)