Honestly, 40k already had the seeds for it - the Sisters of Battle, female and mixed-gender Imperial Guard regiments, planets full of black people and not!Samurai and Native Americans. This is further helped by the fact that the name of the game was 'make your own dudes' - even if the lore didn't mention it, you could easily make your own regiment of super buff not!Catachan women.
Now they're just shoving it in your face more. You hate it because it's more strongly associated with a political group that you disagree with, but if it had remained as subtle as it had been you wouldn't have minded it and may have even championed it, either because you want a Sister of Battle to crush your head between her thighs, or because you saw it as a way to share common ground without 'losing' to a political ideology.
But now we make everything political so we can't have nice things or compromises. It's all 'there are Nazis in 40k!' and 'the fat tumblr women are making us give up our game reee.'