here’s a reason why the BMJ have banned the sentence “more research is needed” at the end of academic papers. That’s because it means nothing and adds nothing to the topic in question. If you have identified gaps in the knowledge then your paper is the place to be suggesting how we should fill it!
The same could be said for the sentence that begins many news articles - ‘A study has shown...’. The problem with that sentence is that is skips the most important part of any study; that is; was it set up and run properly to investigate what you are about to say it does?