For a lot of, the reply to this query is fairly cut-and-dry: sure they need to. The Marvel Cinematic Universe is a superhero universe, and in superhero universes, there’s a clear-cut judgment of right and wrong. There are heroes who’re good and villains who’re dangerous. If a villain kills somebody, it is an act of wickedness as a result of villains do dangerous issues. If a hero kills somebody, it is an act of righteousness, as a result of heroes do good issues. In relation to violence in a superhero world, all the things is permitted, as long as one has been clearly outlined as a hero.
When Thanos and his military kill heroes on the battlefield, it is a horror. When Iron Man makes use of the Infinity Stones to wipe out hundreds of troopers on the identical battlefield, it is a triumph. And it is a triumph as a result of Iron Man is a “good man.” By no means thoughts that hundreds of individuals are actually lifeless by his direct actions. Additionally by no means thoughts that Iron Man might have wished for something with the Infinity Stones, and actively selected to make use of them as an instrument of demise.
The Guardians of the Galaxy are, in fact, the flippant “sensible guys” of the MCU, so their comedic disregard for sentient life was initially a part of the gag. Rocket Raccoon frequently stole the prosthetic limbs of disabled individuals and laughed at their misfortune. The Guardians weren’t essentially good, upstanding residents, however rascals and jerks pressured into making good selections by circumstance. Over the course of their a number of movie appearances, nonetheless, the Guardians softened, changing into extra sympathetic to 1 one other’s plights. They have been outsiders who, resentful of being rejected by society, huddled collectively for heat of their unusual, caustic discovered household.
One may assume this could instill in them an aversion to killing. No such luck.