> Also note that KO has build-in templates so no one
  > actually forces you to put bindings inside your static
  > (or server-side generated) html.

And that's the problem. Moving bindings out of html starts to make thing ugly, trying to move away to some other templating engine makes them even more ugly and in the end it is just more simple to take Backbone.js and do it all there. It makes no assumptions about your templating engine, your DOM manipulation lib, etc. Not to mention it is smaller few times. KO is fine if you follow its golden path, but that path is quite narrow.