Ability to have plugin sets (a set of plugins) that run as a separate application, i.e. I could make a dedicated epub creator with a whole bunch of features and release it as its own separate application, but people can also take any feature from my epub creator and use it in atom because each feature of my epub creator is just an atom package. an example of another text editor that implements this idea, is https://mefrio.wordpress.com/2013/05/25/euclide-ported-to-scratch-2-0-improvements-coming/
I hope this idea make sense.
and yes I know you can use atom-shell but it isnt super easy, I cant say I want atom without these packages (ie the language ones etc) and I want these packages (the packages which make my custom text editor special)