This was very well written. I do have to insert my two cents, however rhetorical your questions may have been. The reason people fight at every little turn is because they don't know how to create dynamic conflict---- that is, when the plot itself doesn't involve enough interesting conflict (which does NOT mean fighting), it tends to be vented purely through the personality of the character. With enough conflict in the plot, the person can focus on making their character's personality dynamic and depth. So all in all, when you come across problems like you listed above, it's because the general plot is not well thought out or they're playing just to play. Now, what I have to say on that is that in some instances I just let it go. Roleplay is meant for the enjoyment of players, no matter how stupid their tastes are. As long as they don't infiltrate my plots, I am okay with whatever they want to do. It does degrade the environment of roleplay overall, but what are you going to do? All I can say is that's a case I would have to take on purely based on whim and hope it wasn't a waste of time. Haha.

I would have to second Kestrel's point of view. There are a number of possible reasons a character might instinctively react to conflict by putting up his dukes:

-He might have been raised in a society that prized combat prowess above all else, or is descended from such a culture (in fantasy games, half-orcs are prime examples of this).
-He might be paranoid and assume the worst in people, as with the Larry Who incident in the first post. People with trauma in their background often assume this mantle when the specific incident that brought said trauma on them is brought up.
-He might be fiercely competitive to the point that he can't stand anyone getting the better of him in anything. These are the sort that throw their controllers across the room every time they get sniped in Halo, if only because the guy that's handing him his ass isn't necessarily in the same room. Alternatively, he could just have anger management issues.

Indeed, the struggle within such a character that wishes to gain control of these violent impulses can create additional conflict within the story: It's for good reason that the outcast that struggles against the weight of tradition is a common heroic archetype. The best part about this sort of conflict is that it can't be solved with blades, and indeed a handy trick for making an interesting personality for a character is to include this sort of dichotomy in their attitude. For example, a paladin might have a larcenous streak, sometimes swiping the occasional bauble or trinket when he can justify it to himself.