Some thoughts:
"
I'm a soldier, not a diplomat" -
James T. Kirk (
TOS: "
Errand of Mercy") But, as TNG evolved, the writers had to remind themselves that the Officers aboard were essentially " Scientists, not soldiers".
I guess their Charter has a lot to do with how they are perceived and how they perceive themselves, Militarily: 5 year mission, to explore.....
Well- honestly, i'm hard put to think of soldiers who explore... So it's a conundrum, a paradox. Soldiers generally do not "explore", and Explorers are generally not "soldiers", tho they might be accompanied by some (as in the Military SEAL-ish guys on enterprise after the xindi attack); and explorers generally need to be able to defend themselves- tho anthropologists are more wont to immerse themselves peacefully into a new culture.
interesting topic.