It's because this supports plugins which are intended to interact with other user-space programs in order to allow for cooperative resource management. These pl

It's because this supports plugins which are intended to interact with other user-space programs in order to allow for cooperative resource management. These plugins would be much harder to write if they had to be implemented in kernal-space (you couldn't use standard user space libs for making RPC calls, would be easy to introduce kernal corruption if you don't know kernal programming). So yes it's for development reasons but not to allow for a faster POC. It's to allow non kernal devs to easily write plugins.