Have orcs ever truly been irredeemably evil? Because Tolkien said no.
Shagrat and Gorbag weren't angels but they served Sauron out of fear, not malevolence. Deep down, even they just wanted to be free to live their lives somewhere "free of big bosses."
Who is the most irredeemably evil trope in modern times? Hint: It's the Nazis.
The traditional way to show Nazis is the good ole "Raiders of the Lost Ark" Nazi. They're cannon fodder. Action movie orcs, if you will. They have ranks so you can have the stormtrooper, the big bald bruiser, the truck driver, the commandant, the SS officer, etc. And that's fun, especially if you need a baddie for an action story.
But what if you want a different story?
Imagine a Nazi spy/war profiteer. He's still a Nazi. He makes arms for the Nazis and spies for the Nazis. He helps the Nazis and is a member of the Nazi Party. On the surface, that's pretty evil. Can you tell his story without him being completely and eternally evil?
That's the dilemma with allegedly inherently and eternally and irredeemably evil races. You can't tell that story. And those stories do exist and are often fascinating and enjoyable.
It's the Darth Vader principle: that even within the most evil character there is a spark of good that leaves open the option of a redemption arc.
For story purposes, even Nazis and orcs can begin to be redeemed. See Oskar Schindler.