Aenghus
Explorer
At a guess, as I'm not [MENTION=6802178]Caliburn101[/MENTION] , I think it's a combat-as-war vs. combat-as-sport thing.
Cali, I suspect (and please correct me if I'm wrong), sees combat as war almost all the time, save for a few exceptional situations as posted.
I'm also in this camp. The as-war aspect and risk of death (or worse) is what makes it entertaining and (usually) suspenseful; vastly more so than it would be were it sport without the possibility of lasting (or any!) consequences.
If a character is plot-protected then any combat - no matter how superficially exciting or suspenseful it may be at the time - is redundant, and merely an exercise in going through the motions; because one way or another the end result is preordained*. This is even more the case if-when the player is aware of said protection.
* - that the PC will survive. The manner of that survival - as a prisoner, as a slave, as a triumphant victor - remains in doubt; but as the plot protection is almost certainly going to extend to being afforded ample opportunity to escape from prison or slavery or whatever it still doesn't matter in the grand scheme of things: the PC will still win in the end.
Heroic, perhaps....and fine once or twice, but it quickly loses its appeal if done every time.
Lan-"and yes, I find the 'good guys always win' aspect of movies books and other media also gets boring sometimes"-efan
As I and over people have mentioned more than once, if there is some sort of script immunity in operation in a game the play is about stakes other than mere survival. The very script immunity allows players to feel safer forming bonds with NPCs and laying down roots in setting, safe in the knowledge that a random deathtrap won't meaninglessly kill them the next day.
The village can burn, the beloved npc can be hurt, killed or kidnapped, war can break out etc (I'm assuming the feelings are "real, not faked here). There's a whole multiverse of stakes other than personal survival to play for.
I find "combat as war" to degenerate into a "PCs escalate first" until one side is wiped out cycle that I see as just as unrealistic as the alternatives.
Negotiation and treaties aren't an unrealistic way to temporarily or semi-permanently end hostilities, but IMO they are less likely if the PCs are just trying to wipe out the opposition (which can seem rational if the PCs only care about themselves and don't give a damn about the setting).