Hi there,
I’ll admit I have never thought of this but I will add it to the feature upvote. You’re right - project files are designed to be freely shared and modifiable. Trust me, I get why it would be frustrating to have people claiming your work as their own.
What I would recommend for now if you want to create projects files for others while asserting your copyright, is to put any components you want to protect within a macro and lock it. A locked macro cannot have its author, description, etc modified.