The problem is that "best" is subjective. I think one could more accurately say that they're trying to develop an editor that is easily extensible with technologies familiar to many developers.
i.e. your perception of what they want Atom to be and the reality of what they want Atom to be are probably not the same.
My take? Revisit this in five years. I bet it'll be one of the richest ecosystems in software development. As one who has written Atom plugins (live unit testing w/ real-time feedback), I've never encountered such a developer experience until Atom.
Lets say if one of the main goals was to build a very easily extensible editor, one might still choose to build it on web technologies.
While I don't use atom, I can see the reasoning. Since I'm comfortable with webdev, the barrier to entry for extending atom is much lower compared to other newish editors.
I love the drag/drop sidebar but If this update doesn't inprove the editor significantly, i will delete it.