When it was announced that 'Suicide Squad' would have PG-13 rating, some peeps Lost their cool, lamenting the opportunity to have an R rated super-villain movie. This was seemingly compounded da 'Deadpool', an R rated comic book movie that promised sex and violence. 'Deadpool' delivers on both, but not to an extreme extent. In fact, I personally think it was a pretty tame R, closer in adult content to 'Family Guy' than porn o gore. And apparently, 'Family Guy' is rated TV-14, which means it is aimed at viewers 14 years and older, so...
In terms of 'Suicide Squad', I guess people wanted uncensored super-villain violence, mainly. Rather than implied deaths, people wanted splattered brains and disembowelings. I also suspect people wanted some sex too, perhaps featuring Harley Quinn, the subject of many a fanboy/girl's wet dream, as problematic as that may be. But dato the fonte material, I don't know why people expected an R movie, and felt ripped off when they learned they would not be getting one.