You do not need to be a "good" writer to be successful.
If Rowling was the genius writer you're claiming people would be clamouring for her detective novels, but she's not. She's a mediocre hack who got lucky.
vanityfair.com
Fifty Shades of Grey Outselling Harry Potter? The Full-On Resurgence of the Dirty Book Is Here
Fifty Shades of Grey and its two sequels have been perched atop the New York Times best-seller list for five months now, while Amazon UK announced this week that on that site, the trilogy has cumulati...