Hmmm... Haven't had a chance to play it yet, but I would like to remind everyone that human beings are capable of sympathizing with some pretty terrible people, as long as they're interesting.
To quote; "It is the difference between The Godfather Part 1 and Part 2, between Inglorious Basterds and Triumph of the Will, and between Just Cause 2 and JFK Reloaded. In the former examples, the audience can get behind the anti-heroes depicted for whatever reason and condone their admittedly awful actions, but in the latter group, the subject matter or the protagonist's morals are skewed too far from the norm to be comfortably witnessed."
I think this idea is under the yolk of a few preconceptions. Maybe the events we're witnessing aren't supposed to be pleasant. We don't need to condone their actions to empathize with a character, we just have to understand them.
The characters in The Godfather are not anti-heroes, in fact, they're not heroic at all. Most of them are concerned with looking out for their lot and ensuring their continued supremacy. Simply because they aren't raging psychotics doesn't excuse the fact that they regularly commit murder. And you know what? that's okay.
We don't empathize with Michael Caroline because we admire him, we empathize with him because he's human; he has desires, fears and dreams.
Even a character as reprehensible as Kratos from God of War is sympathetic, and not just in spite of his faults, sometimes because of them. The fact that he's such a monster, and the fact that he came by his cruelty honestly, that even he once had people he held dear, is what makes him a tragic figure.
Kratos is not defeated by his enemies, he is defeated by himself. What can drive a person to madness? Can we escape from our own guilt? Should we even be allowed to escape from what we've done? These are questions that the story of God of War evokes, they're questions that couldn't be asked of a heroic character acting with justification. And because Kratos is humanized, because we can understand how a human being like us could be driven to commit these terrible crimes, we don't ask them simply about him, we ask them about ourselves, not about a single human, but all humans. We are reminded that depravity is not comfortably distant from our nature, but uncomfortably close.
Kratos's actions are never justified or condoned (At least in the original game). God of War was uncompromising in it's characterization; Kratos is a vile, sadistic, hateful, ruthless, black-hearted, sociopathic monster of a person. But Kratos is still a person. He didn't spring fully formed from the head of Zeus, he became the person he is, like any human could.
I don't know if this is true of the protagonists of GTA V, but I think it's erroneous to suggest that a character's actions need to be justified. In fact, I would argue the opposite; a story shouldn't be biased towards a character, good or evil. It should neither condone nor condemn anyone's actions. The actions should be shown simply for what they are, for better or worse.
By trying to convince an audience that a character's actions are correct, a story replaces a characters perspective with it's own perspective, and denies itself the opportunity to deepen that character. I don't want to know why the writer thinks this is an ethically advisable or inadvisable course of action, I want to know what the CHARACTER thinks. The character is the one I'm interested it, the character is the one who inhabits and drives the story.
Now again, it may be that none of this is true of GTA V, that Franklin, Michael and Trevor are cartoonish, two dimensional caricatures lacking any humanity or depth. But if that's the case, it's not because they're terrible people, it's because they aren't people at all.
Stories shouldn't turn away from the truth because it's uncomfortable, in fact, unfortunate truths are the ones that need to be confronted the most.