Nedry was definitely a greedy scum bag and Muldoon's and Arnold's blood are on his hands as a result of his actions. But since there is no clear indication he had murderous intent, the worst you could nail him with in court is manslaughter. And while manslaughter is a serious charge, it doesn't typically carry the death penalty. Had Nedry stood trial afterward, I think a 25-30 year sentence would have been good enough.
Ludlow's only flaw was wanting to build a dino theme park in San Diego. Misguided sure, espacially after the events of the previous film, but by no means evil.
Hoskins was definitely arrogant and short-sighted, but at his worst he was a well-intentioned extremist. His plan definitely backfired big time and people died as a result, but that doesn't make him a cold-blooded killer.
All these guys suffered from the deadly sin of greed, but Mills is the only one who actually committed a murder in order to advance his monetary interests. When he did that, he crossed the line in a way that none of the previous antagonists truly did. Honestly, he was the only one I wanted to see devoured. Getting chomped by the Tyrannosaurus was definitely karma, not to mention Rexy crushing the Indominus bone he was attempting to smuggle as an added insult.