Of course voting is useful. But then again, I don't put a big glow to it. Voting is about as essential as washing yourself. It's something you're supposed to do. Now, you can't go around bragging, expecting to get props because you voted. That's stupid.
It is immoral from almost any point of view to refuse to defend yourself and others from very grave and terrible threats, even as there are limits to the means that can be used in such defense.