Filing a police report helps you for any future problems such as arrests or litigation. Cops don't want to do the paperwork on a crime that most likely won't be solved. I know this as I used to be a Deputy...it's a pita....but I know it's also an obligation. See, having a report on file will help you in future cases. If this were to happen again to you, they can go back and pull the report from this and add it to the new report. From that they might be able to see a pattern....not just from yours but from other's reports as well and make some sort of connection to whom it might be and make an arrest. But without your report, the connection and arrest might not be made and/or charged with a crime that happened to you. If it does happen to you again, the first thing they are going to ask is did you file a report on the first incident and you're going to have to tell them no. No report....no crime....it won't be taken seriously.
All I'm saying don't let them tell you squat. Fill out the report, get it done, get it on file, and move on. It might serve to be useful in the future.