I think it is rooted in self-righteousness. They have their little tin god Jacob telling them what is right and wrong and puffing up their heads with the notion that they are better because they are in his little model society that exists to prove the goodness of mankind. This makes them think "We are good." From that basic assumption it is only a short step to "Those who we oppose are bad," and then we get to "Whatever we do to them is justified, because they are bad, and our goodness must be protected no matter how harshly." All those people who were killed out of excessive caution and whatnot? Necessary casualties when compared to the awesome and elite Jacobite society.

The only problem I have with that scenario (the Richard's tool scenario, I mean - it had occured to me as well) is that Jacob wasn't actually working through tools and minions yet. The episode seems to imply that Richard is the first time he decides to use a henchman.

Well, these people are hardly innocent bystanders - they have been serving the cause that keeps him imprisoned all these years on the island, and he gave them a chance to leave. There is no indication that he harmed the stewardess from Oceanic 815 whose name escapes me at the moment, or anyone else who took him up on his grace period. The people he killed were the ones who chose to blindly follow the dictates of his dead (and possibly evil and certainly douchey) jailor.

And we don't know that it was Smokelocke who did it. For all we know it was a property of the water. Presumably the same thing was done to young Ben (after he was shot by Sayid, let us not forget) and Richard made it sound pretty dire last season. Maybe Sayid's history of willingness to do horrible things in the name of good indicated a corruptibility on his part. Recall that he tortured "Henry Gale" and was ready to go to town on Sawyer in the early seasons. He undertook a series of assassinations of people solely on the word of Ben Linus that they were dangerous, and was willing to feign an affectionate & intimate relationship with one of his targets in order to get close enough to kill her. He appears to have turned against Ben mostly because Ben suddenly ended the killing and left him anchorless, not out of moral revulsion for what they were doing. He attempts to murder Ben as a child, despite Ben doing no great evil since Sayid had been working for him (though he does not know of Ben's attempt on Penny's life). While these might all have been for altruistic reasons, he is clearly a guy who is willing to bend even his own standards of right and wrong in pursuit of a greater good. It is just as likely that whatever infected him was able to do so through his own corruptibility as Smokelocke's influence.

Interesting questions, but he shows no sign of the behavior you attribute to him. He's a lot more forthright with his associates than Jacob, with the latter's cultivation of his mystery and demands to be blindly followed on faith.

Sure the potential for great goodness is there, but most people still fall way short of it, and indulge their worse impulses far more often. What is more, in groups they degenerate further. Note how a period of solitude is almost universally necessary in every fictitious or legendary or mythical epiphany or attainment of enlightenment or moment of self-realization? I think Jacob and people with his view see the possibilities and blind themselves to all else, while people like the MIB see those same possibilities and how easily people ignore, reject or fall short of them for the worst reasons.

I also think you attribute a little too much malice and tyrannical attitudes to a guy, who, as bad as he may be, has never directly expressed malice toward anyone other than the man who is keeping him on the island (and by extension, anyone who would take his place). I can't help but think that Jack would be entirely sympathetic to this agenda before his own escape, and that any number of the passengers of 815 and Juliet might agree with him.