Why does the Pope not issue letters on the lines of Pastorals?

Catholic Bishops have been, from time to time, issuing a Pastoral Letter, often called simply a pastoral, which is an open letter addressed to the clergy and/or laity of a diocese, containing general admonitions, instructions, consolations or directions for behaviour in particular circumstances. Each letter would be read on a designated date in all churches across the diocese. One is curious to know as to why the Pope does not issue such letters, in spite of the fact that information technology has enabled us to download any letter issued by the Vatican, in any part of the world and to have read it out in churches on a designated date. In fact, such letters would go a long way in guiding the clergy and the faithful alike on different issues of importance. My question therefore, is : Why does the Pope not issue letters on the lines of Pastorals to all churches across the globe?