As a bit of history, most of our team is made up by old-school desktop engineers with a background in native desktop development (and we still have a pretty decent amount of C++ and ObjC running in our app). Decompilers these days are pretty impressive – seeing the implementation of most desktop apps is fairly trivial.
This is just a personal statement, but I never had trouble with the files being there. They're currently present to support some outdated and soon-to-be-replaced module resolution, but I'd give this advice: If you're shipping logic to users, make your peace with the fact that it can be reverse-engineered. Sure, opening a source file is a bit easier than having DotPeek decompile your DLL, but it's pretty easy either way.
In other words: My stuff should be safe and secure whether or not an attacker knows how I implemented my logic.