About verbosity: you needed to define classes for so many things. Eg you want others to hook into processing in certain places. So you create a listener interface with some methods. And the provider needed to work with those, and the consumer also needs to work with them.

In modern Java maybe you can make do with functional interfaces and lambda, but it doesn’t always work I think.

And in emacs: the provider does run-hooks, and the consumer defines a function and says add-hook. Done. Very little ceremony.