I mean, part of it is that we're introduced to these character as Victims. We don't get to know them as free people making bad decisions, and in doing so finding themselves in Waller's crosshairs. We meet them in prison, with bombs in their heads, forced to do Waller's bidding.
We're informed that they're Villains, but their villainy isn't onscreen. It's barely even described, it's just part of the premise that the Suicide Squad is made up of supervillains.
It would probably be different if we'd had a couple years of Comic Books showing Bloodsport fighting Superman by putting kryptonite bomb vests on random civillians and throwing them off skyscrapers so he could shoot Superman when he flew by to catch them.