I don't really get the purpose of this. It's not hooking into anything to work as a middleware and not doing anything special to make a thing a plugin. It's just sugar for a plugin(actor, args...) call. Why would you want an extra function with the indirection and overhead of adding the slice/apply calls?

With a plugin interface its easy for any one to add or build on top of it, for example adding features like reconnect, error handling, etc (We needed these features and added them as plugins). I do think its a plus that will not hurt but bring options for the community to extend. Of course I can use the Actor.on('actor', function(actor){ actor.reconnect = function(){ } }) but I fond it more convenient todo actor.use(function(actor){ actor.reconnect = function(){}}). Yes the slice/apply jazz can be ignored, and it can be simple as:

Actor.prototype.use = function(plugin){
  plugin(this);
  return this;
};

Its ok if you don't want to add it, but I really don't see a reason why not. Anyway is ok!