Frankly, I doubt that people who plan to blow themselves up along with their targets would be 'happy' to do it for only the symbolic effect. I have always wondered why people so often kill the one who 'wronged' them before killing themselves. If you literally can't live without that person, why not just remove yourself from the world and let the other person be? If you're gone, you needn't concern yourself with that person anymore, right?

The same way with attempting to achieve political goals: it takes a good deal of hatred before you are willing to off yourself along with others. Not to mention the dehumanization/demonization of your targets.

The self-immolation by monks, primarily, in political protest is quite different. They generally have been done by people who believe in peace.

All my opinion, of course.