I don't know why but I hoped for more horror and instead we got comedy lol
That's not really Nurgles style. The entire faction is centered around the idea that the cycle of life and death brings some happiness and joy to those who embrace it. It's weirdly positive for a Chaos God, but most of these creatures are blissfully unaware of the havoc theyre wreaking, or how their blight-ridden appearance and pestilence affects others. They wanna play and frolick with you, and if you drop dead theyll quickly find a new plaything to have fun with, while your body becomes the nurturing ground for other forms of life. Maggots, insects, and even bacteria are all alive, after all, and from death sprouts new life.
So basically they're having a lot of fun while murdering the shit out of you, and not because of the pain they're causing.