My humble opinion is that a developer should brand their module. Establish trust and awareness of who they are online. There will always be thieves. Branding is a feeling. I trust XYZ developer. It's up to us as a community to write about and talk about pirated, commercial open source pitfalls. Hidden or malicious code blocks inserted to serve botnets for example.
I believe you only copyright the images, stylesheet and documentation. Even possibly, unique function names. What is everyone's opinion on opening up the core of your module to github for others to fork and contribute? You could install Gitlab CE? Gitlab Enterprise is open sourced. But, if you want all the bells and whistles, you pay for it. But, people who are fans of Gitlab, regularly contribute code to the enterprise version. Corporations have a vested interest in seeing the whole product improve.
Is Gitlab a great example of commercial open source?
There is great power in the wisdom of crowds. If you remember a game show on US television entitled, "Who Wants To be a Millionaire", the contestant was allowed to ask the audience or phone a friend. Astoundingly, their friend got the answer correct 63% of the time. But, this will blow your mind. Answers from the (crowd) audience gave a correct answer 92% of the time.