Not that it wasn't mature before, but putting ratings and warnings on books has long been controversial, and definitely wasn't done on earlier editions. They had to know they'd be evicerated by fans if they released it as anything less.
Dark Sun returns in 2027 as Dungeons & Dragons' first mature rated settingDark Sun is returning as a Dungeons & Dragons campaign setting, and Wizards of the Coast isn't shying away from the world's adult themes. Wizards will release two Dark Sun books, one of which features...www.enworld.org