Don't generate source code. Give me a library that can take the metadata as an argument and generate a the desired code as an object file/in-memory class.

Automatically pooping out source code that is customized just makes more LOC to maintain. Having tools that poop faster just means that there is more to shovel when I go to maintain the application.

If the metadata to code transformation is really solid, what I get is less code to maintain, and the ability to rapidly port metadata generated code between langauges/platforms.

Compare, for example, @ngrx/data and any of the 80 million schematics that ship for Angular development.