Well, I think true self-actualization is impossible. It's only an ideal goal to be worked towards, nothing that can be achieved in the current reality. In working towards it, you are simply stabilizing your ego and making it more functional by broadening what it encompasses; basically, not painting yourself into a corner. Over-identifying with your projected self can be a problem because then you become inflexible and that creates conflict. That also makes your ego more vulnerable and unstable because it gets threatened very easily (where personality disorders and mental illness can come in to play).
I think MBTI is a useful theory that can open the door to a self-examination and introspection that encourages movement towards self-actualization. It's also a big help in a basic realization a lot of people don't grasp: other people think differently from you, and it's not better or worse. That in itself can clear up misunderstandings and encourage positive growth in relationships.
Of course, like anything, MBTI can be misused. If someone thinks, "I am xxxx type and that's why I am this way and there's nothing I can do about it" then they are over-identifying with an image of themselves.
If you really think MBTI is "death for society" though, then turn on the news - there are far worse issues in the world.