In my C++ simulation platform, I load DLLs with user-made plugins that each get their own thread and update loop, and all cross-plugin state access is controlled by strict mutexing. I want to be able to run a Python script as a replacement of C++-coded behavior, with custom C API function bindings constituting the only connections with the outside C++ state.
Enabling easy ways to embed Python code almost as if it is translated to C/C++ will likely enable all sorts of scripting schemes for game engines and other multithreaded C++ applications.