Perhaps, but that's a complicated situation. Do we want to be able to identify criminals and take them off the streets, or prevent SOME of the crimes they commit while allowing them to continue criminal activity with others (e.g., those who don't have iPhones)? Should Apple be in the business of referring text messages directly to law enforcement without the victim being involved in the process? How much invasion of privacy is acceptable? What happens when a system starts interfering with legitimate messages (e.g., two consenting adults trading nudie pics with each other)?
These are just a few of the questions that have been raised in the past. I do agree that building in a reporting function is a good idea.