Flint Marko never really gets his comeuppance
That's one thing that really pisses me off about this movie is that Sandman doesn't really answer for his crimes. It's like because we're given this sob story about him having sick daughter and because he didn't really mean to kill Uncle Ben (and Peter therefore "forgave him") that automatically let's him off the hook.
That doesn't change the fact that Sandman was and will likely always be a criminal. Sam Raimi and company seemed to forget that the audience wants to see the bad guy get what's coming to him regardless of how you try to spin it. Doc Ock had to answer for his sins in the previous movie no matter now sympathetic he was made out to be (he was only "bad" because his wife died and his brain got fried in his science accident) himself.
What's not to say that he'll continue to rob in order to fund his daughter's medical bills? And let's not forget that he was an accessory in kidnapping Mary Jane.