Yes, but the code that uses this method is much more simple than those. It is quite tricky to get right. 
Also there might be some UI consistency but I'll try to fix them with pure css. 

You make a good point for non metadata. I'll see if I can find a way to do that. 

Another point, what would you thing of trying to see if those js-plugin could be installed with npm ? 
It is a Javascript package manager that deal with dependencies, allow testing... etc etc we could just require some supplementary stuff to autodetect js file as plugin and it would allow require stuff like underscore in plugin. Thought ?