It would make the monospace stuff easier because then the addition would happen inside the Joplin markdown parser and I wouldn't need to do any hacks on the plugin side.
It would be interesting to have a system for default plugins, there are a few plugins that it seems like everyone is using (Note tabs for example) it might be beneficial for new users to have access to those by default. It would also enable a path for stripping out features like templates and building them as plugins.
To clarify, I'd be happy to implement some of the functionality from this plugin into the core Joplin experience (the monospace stuff in particular). But I would prefer to keep the core part of the plugin as a plugin.