Author here: it wouldn't have been. Sure, it would be nice to have a native version, but that is a lifelong maintenance burden, and ExifTool is already the best at what it does and stays up-to-date with file format changes.

By completing this work, I can use ExifTool in any environment now - and more broadly, there is now a portable, embeddable, and sandboxed version of Perl that others can use in their projects. I can think of a lot of use cases, and helping other developers makes any hardship I endured worth it.