Mass Effect 3's ending is RACIST!
The one common element in all the endings is that you will meet an entity known as the "Catalyst". Set aside all of the other plot holes and minor complaints, and focus on the Catalyst for now.
This is the entity that created the Reapers. This is the entity that is
directly responsible for the genocide of multiple sentient races over tens of thousands of years. It is his fault that Earth, Palaven, Thessia, and the Galaxy is burning.
The Catalyst is in fact a
war criminal on a scale worse than any of our own real-world tyrants. Hitler's gas chambers, Genghis Khan's campaigns of extermination, and Tamerlene's pyramid of skulls is nothing compared to what the Reapers have done. That it tries to disguise itself as a young child does nothing to exonerate it of the magnitude of its crimes - it's actually sickening. It's like Hitler having plastic surgery to look like an innocent child.
Even worse, this is an entity that attempts to justify its genocidal actions - in a way that is bluntly little different from the real world genocide of the Jews.
It uses euphemisms to describe mass murder. It uses the term "Chaos" to describe
people, as though they are a problem and not living, breathing, beings. It calls its actions a "Solution", just as the certain people called the Holocaust their "Final Solution". It even goes as far as calling the the liquification of corpses into Reaper components as "Ascension", no different from how the Concentration Camps collected the hair and skin of the dead victims to use as furniture components.
Even worse, the premise of the Catalyst is fundamentally a
racist premise. It boils down to "Organics and Synthetics are so different that they will always end up destroying each other". Really? You are now judged by your component parts - metal or protein - instead of the content of your character? How offensive would it be in real life to hear someone say you should be judged by the color of your skin?
To top it all off, the player is not allowed to question its actions. It must stand idly by and accept its justifications. You are not allowed to tell it that is wrong. Mac Walters and Casey Hudson actually thought this was a
good thing too