The aspect of the argument that I'm finding interesting is the presumption that the adventuring party is nothing more than a group of bandits with powers.
Isn't that really what all versions of D&D are mostly about?
For example, look at 4E XP. The vast majority of it is about 10 encounters per level or 290 encounters overall to get to level 30.
290. Even with 2 encounters per gaming session and one session per week, that's 3 real years of two fights a week.
3E was 13 encounters per level or 247 encounters from levels 1 to 20. More if going to Epic.
Look at 4E powers. The vast majority of them revolve around combat. 4E stripped out many if not most of the miscellaneous spells of 3E and turned them into rituals that cannot even be used in combat for the most part.
Look at the Monster Manual. Many of the monsters are sentient (the vast majority ~340 have Int 8 or higher, just like the PCs).
Look at magic items. They are required to balance the encounter math at higher levels. Look at the parcel system. Designed for looting.
The word roleplaying shows up 31 times in 320 pages in the PHB and 32 times in 224 pages in the DMG.
It's a footnote.
D&D has historically and continues to be a hack and slash game. Sure, some people throw a bit more roleplaying in or skill challenges in for the reward system, but the game is not heavily designed for that.
It is designed to be an explore, trespass, kill, and loot game.
The game is totally about violence and deadly violence at that. Really little different than WoW in that regard.
How many times do two groups in D&D encounter each other and the DM announces "Roll initiative"? Happens nearly every session in many campaigns.
Can someone make the game something beyond that and take away most of the carnage? Sure. But, very few groups do.
And how has D&D historically gotten around the moral dilemma of PCs fighting sentient NPCs? They called most of them evil (monsters, bandits, outlaws, cultists). When the NPC has evil tattooed on his forehead, it's all good as far as many players of PCs are concerned.
In 4E, the designers even got rid of most of the good races and called them unaligned, just so that they could remove the moral dilemma even more. They also reinforced the concept of "points of light". Society = good, outside of society = bad (as a general rule of thumb). They combined lawful with good and chaotic with evil.
How can anyone seriously consider most groups of PCs to be anything significantly more than bandits with powers? Sure, they might be supported by a king or a sheriff and they might help out others. That doesn't really make them good individuals. Not with the amount of death and theft on their hands. Not when they are rewarded for killing and stealing (via XP and wealth and level increases).
Compare this to a superhero game. There, the PCs do not typically explore (at least not in the sense of traveling around exploring the world wherever the road leads). They do not loot. They rarely kill. Instead, they show up and help others when the bad guys show up. They arrest foes or hand them over to the authorities. How often do Superman or Batman kill foes? How often do they steal? The violence is still there, but the murder and theft aren't.
Superheros are heroes. D&D PCs are typically thugs, even if they are helping out other NPCs. They kill. They steal. Sure, there are occasional exceptions. But, those are the exceptions.
If PCs were really heroes who only killed when absolutely necessary and never stole, then different types of Pacifism would fit in better into the game system and we wouldn't be having this discussion.