The answer to this question is very simple: yes. We consider it an “obligation” if you wish to upload documents relating to commercial correspondence with your suppliers or customers as proof of copyright.
The reason why we invite you to password protect some types of documents you send us is easy to understand. Imagine being contractually bound not to disclose some parts of the contract between you and the company that provided you with a component of your creation. Or the tender specifications you participated in. If you send them to us, we encrypt and deposit them on the blockchain. So, I’m “safe” … until they stay on the blockchain. The problem arises when they have to leave the blockchain because for example you have to use them as proof of copyright in a dispute. In that case, of course, you will have to show them to the judge or the referee. But, if you do not intend to make the content visible also to the IT expert who will have to confirm the certain date, just enter a password and the contents of your files will be safe from prying eyes.
Operationally speaking, to make things simpler, we recommend gathering all documents that need password protection and zipping them, adding a password to the entire zip file. If you don’t already know how to do it, there are many websites that explain the procedure to follow. As illustrated in the well-known site of Salvatore Aranzulla (see here), using free compression programs like WinRar, in a couple of clicks files are aggregated in a single zip and protected with a password.