I myself am not the biggest fan of grimdark but hey y'know, I'm not gonna go around and yell at you for liking it. Y'know, you can like what you like, if it doesn't bother me, it really shouldn't bother anyone else just for liking it.
Unless the person who likes grimdark shoves it into other people's faces who say they don't wanna hear about it then that person kind of deserves it.