The aim of your writing should be to communicate as clearly as possible. The language should be formal, but, above all, understandable.
Think of it this way; when a busy academic downloads your paper, it's probably one of many they've downloaded to try to read before their next meeting. They have a limited amount of time and attention to spare, and if they don't understand what you're saying quickly, they'll move on to the next paper and forget about you.
But it's easy to forget this when trying to dress up your research in high-level academic language. If the language obscures the message, then it isn't serving the basic aim of communication. Some academics do this deliberately, confusing the reader to disguise a lack of actual content, others do it inadvertently because of a lack of confidence and some do it just because they think it's how academic writing should be.
It's easier than ever to reach a global audience with your research, but that audience is overwhelmed by the sheer amount of information available. If you want your work to be understood, noticed and spread, write as clearly as you can.
