I agree that there is loss of value when you can not get the source of a bought product as a developer. Not only is it an obstacle while developing, it would be hard to do quality checks and even security checks to make sure an asset is not infected. EPIC does not guarantee the safety of assets (legal matters, quality, viruses and so on.). It should be a big no no to buy and run code like that in a business.
@elemento
In my earlier post where I responded to the desire of disabling the export button I linked my post about sales models. This new link takes you straight to an example of a few sales methods where you can both protect the end product without loss of value for the developer. For example, you can have a plugin hosted on a private server to which unreal developers make API calls (to convert data, as a service such as text to speech or translation). It’s one way to sell where it can be a win win for both sides.
@RecourseDesign
Sadly the marketplace is still lacking in ways you can offer services and licenses to make it a real win-win. There is a “buy once, do whatever you want with it” attitude among buyers. When I put my code on github I find it much easier to deal with (and include) terms, copyright and licenses. Same goes when I personally contact people and set up an agreement. It’s much more flexible. “should it remain open source? may it be used commercially? must the license be preserved? can the license be changed? may the code be altered? do i pay for the product, a subscription, a per use rate, a %, a per hour rate? What extra service options can I get? What about terms, warranties, refunding etc.?” questions. I see loss of value for both sides in that the marketplace does not provide more options to choose from.