Sometimes there will be straightforward instrumental reasons to be non-cooperative. If you're the only person who knows the code to the doomsday device, you shouldn't give it up to genocidal maniacs no matter the cost to yourself. Other times, you are replaceable, and so the instrumental benefits will only be realized if you can be confident that every other potential victim will be similarly non-cooperative. (It's striking to think that slavery and tyranny could not exist if the victims steadfastly refused to cooperate. A populace might be slaughtered or imprisoned against their will, but they cannot be enslaved or exploited unless they surrender their will to their oppressors.) Alas, humans are not psychologically constituted to be such threat-ignorers, and in light of this general fact, resistance by any one unusually strong-willed individual will likely often prove (instrumentally) futile.
But it's interesting to consider whether resistance to an evil-doer's will might be non-instrumentally valuable, and hence potentially worthwhile even in cases where defiance has no (further) effect. It certainly seems that way in stories: we admire Kunte Kinte's refusal to submit to his enslavers, and feel that a great harm is done to him -- beyond the pain and physical damage of the whipping itself -- when they finally break his spirit. Defiance seems a way to maintain one's integrity and dignity in the face of oppression, whereas the more comfortable life of submission seems less admirable, less meaningful, perhaps even less than fully human.
That's not to say that we should uncritically accept these appearances though. Romantic as defiance may be, can we give any deeper explanation for why it should be considered of genuine value (let alone a sufficiently weighty value to outweigh the immense suffering it may bring in situations like Kunte Kinte's)? Three thoughts spring to mind.
(1) It may be grounded in the value of autonomy. The defiant agent refuses to accept the unjust dominion of others, so although they may restrict his physical autonomy, he retains an important kind of mental autonomy for as long as he refuses to cooperate with his oppressors. Mental autonomy strikes me as genuinely valuable -- it's important to be a genuine agent, and not merely a spectator in life -- but one might question why choosing to submit to an oppressor's demands cannot be just as genuine a choice as resisting them. (Either way it is, of course, a highly constrained choice. But that just means that the agent is in a bad situation; it doesn't mean that they're not an agent.)
(2) Defiance may constitute a form of virtue. Refusing to accept the slaver's authority may be a way of accurately reflecting the normative fact that the slaver has no rightful authority over you. It is to insist on the respect (and freedom) that is due to you as a person. And that sounds all very nice and proper. On the other hand, cooperating to avoid gratuitous torture does not mean that you accept that the slaver has the right to boss you around -- it might just reflect your prudent appreciation of the badness of getting tortured. One may accept the pointlessness of trying to communicate one's moral standing to an unresponsive audience, without thereby ceasing to believe in that moral standing, oneself.
(3) Finally, we may see defiance as a source of shape and meaning in the agent's life, a way of clearly acting on their values, and accomplishing a kind of "life project". I think there can be genuine value in this, though it may be more "subjective" in the sense that it is just one of many ways that an agent might seek to give shape and meaning to their life. (Perhaps "optional" is a better word.) A slave may focus on raising a family rather than on fighting their slavery -- and though less dramatic, I don't think we should necessarily dismiss this as being a less meaningful way to live.
So, I guess I remain undecided. What do you all think? Is the submissive slave who focuses on raising a family making a mistake? Is the futilely defiant slave? Or is neither option better than the other?