There is a large communication component to information and knowledge work. Proper penmanship is part of that component.
Taking time to properly document your research and analysis often entails handwritten notes. These notes are in turn used to check the correctness of the finished report. That means your notes must be complete and legible.
Good penmanship is the product of practice and concentration. It is also the product of the proper tools. A proper pen for the size of the writing and for the speed of the writing. Paper that is smooth enough for the selected writing implement. Ink that does not bleed through or feather on the page.
Your note-taking must also allow easy photocopying and scanning. I often get faxed or photocopied notes that are illegible. Correcting this is also part of penmanship in the modern age.
I often hear people complain that their handwriting is poor because they have to write fast. This is a poor excuse. If you need to write fast, then learn a simple shorthand system like Quickhand.