There is no variance, no nuance, its only purpose seems to be a form of auditory warfare.
I really, really, REALLY hate screaming mutants. To the point of not wanting to play the game and getting heavily, aggressively BORED hearing it.
Use the Zip It 2 mod to mute them but don’t cry if you get grabbed by a mutant you didn’t know was there.
Modding the game is not a real solution. Having a disadvantage by doing so even less.
It would be great if they added at least two different screams for them so you don’t hear the same one hundreds of times. While I don’t have that much of a problem with them in normal missions, wave of mutants modifier can be annoying indeed.
The sound is the same because the game teaches you to recognize it and get used to it.
So you get better at the game.
imagine the voice actor who had to do it
On further thought, the mutant screaming sounds could(since he(it?) is this Bane-esque chem roided monster) be replaced with Chemlike sounds like Tsssshhhhh…followed by muffled animalistic roar). This could also be used to tie the Mutant into Tertium as some (former) hive scum clan gone off the deep end with nurgle spiked chems.
It’s actually one of my favourite moments when you get the mutie conga line all screaming, pure comedy lol. Maybe it breaks the grimdark a bit but no matter how dire the situation is I find myself chuckling at the absurdity when they all come calling 
There was a time when you could hear nothing but.
Turn your sound down a little. It’s not that bad.