Does a story exploring dark topic make it well written??

I've thinking about this due to a pretty controversial author (harada) I tried reading some of their stories because people always talk about how even though they have taboo things (pedophilia, rape) they're well written but i can't help but disagree, i feel like a lot of people see something with dark and immediately say "it's well written". I'm not going to go indepth about my personal feelings about harada as a writer, I'll just say i'm not a fan but i am curious is exploring dark themes on its own an achievement in writing, going past what most people are comfortable writing and reading? Or does the fact those dark themes aren't written with the proper care make the writing bad?