Code generation is under utilized because most people don't have a build system good enough for it. Traditional make is fine: you just define dependencies and rules. But a lot of people want to use language-specific build systems and these often don't have good support for code generation and dependency tracking for generated code.
Yet another subtlety is that when cross-compiling, you need to build the code generation tool for the local target always even though the main target could be a foreign architecture. And because the code generation tool and the main code could share dependencies, these dependencies need to be built twice for different targets. That again is something many build tools don't support.
Yet another subtlety is that when cross-compiling, you need to build the code generation tool for the local target always even though the main target could be a foreign architecture. And because the code generation tool and the main code could share dependencies, these dependencies need to be built twice for different targets. That again is something many build tools don't support.