Bismillah
Thank you for your question. As people of faith, we connect to our sacred history and the personalities that represent the values of our religion. Thus, while events may have happened a long time ago, the personalities that these events happened to are important to us, so naturally, when recounting the tragedies that befell them, we cannot help but be brought to tears. Such acts of devotion have a positive effect on the soul and this has been indicated in the copious praise for crying over these events in our scriptural sources. Simply put, we cry because it matters to us and we recount the events so that we remember and develop those feelings and are revitalized by the strengthening of our bond with those we love.
May you always be successful