So, I had to look some stuff up and I wanted to share what I found. If I’ve made a mistake, please correct me.
A PAK file is a compressed archive file. Like a zip file, but for larger files.
An unpacker is program used to extract a PAK file.
So, it seems to me that if I don’t encrypt my UAsset files, then all my project assets can be duplicated and distributed by anyone with a copy of my build. 
Is this correct? If so, shouldn’t UAsset file encryption be automatic and compulsory?