I just read a book about personal identity and it gave me insights in different theories about personal identity. But after all, I still don't get, why we should care about personal identity.
Being a philosophy student, I can usually grasp immediately the reason, why we engage in some philosophical projects: What is justice? What is language? What statements follow necessarily, which statements are a posteriori? What is science? etc.
But what's so interesting about personal identity? If I can't remember, whether that guy in the school-picture was me or not, no amount of philosophizing will help me. If the police wonders, whether that guy sitting in that chair was the bank-robber two hours ago, no philosophical theory will help the police to distinguish the real robber from an innocent person. So, the study of personal identity has no practical value. But does it have any theoretical value?
It seems that you are asking two different questions. (1) What is the importance of personal identity as a subject in philosophy? (2) Why should people care about their personal identity? Can you clarify which one you mean (or do you mean both)?
I'd like to hear an answer to both questions, if possible.