Everyone loves a good villain. Sure, they do terrible, terrible things - but in awesome, kickass ways, and generally with a damn good backstory to explain why. While seeing people do good is by no means bad in a comic, it can get stale pretty fast, especially with how cliche a wholesome good guy is in the realm of comics. So a team of villains forced to do good? Pure comic gold.
This is exactly what makes the Suicide Squad one of the most interesting teams in DC - all questionable, controversial film adaptions aside. Having characters who don't want to do the right thing makes for genuine suspense, because we can't predict how they'll behave. It also makes their moments of genuine, unforced heroism all the brighter, for showing it doesn't always take a hero to do heroic things.
Sometimes, this means some awful things happen - the team barely want to rescue each other, let alone random civilians. But between risking their lives, their sanity, and their freedom to do good, the motley crew of villains are heroic far more often than you'd expect.