Can they not also be operated on in the createView() call?
Yes, they can, but you _must_ also pay attention to them inside updateView(). You only get a createView() the first time the view is created (unless it's garbage collected based on non-use), updateView() is called each time.
A real world example:
In the Finance widget when you select the Yahoo! row in the list, we load up the detail view passing in the stock symbol for the view to load. The first time, createView() gets called. If I then hit back in the sidebar and then go and select Apple from the list, the same view gets reloaded, but this time only updateView() gets called and the new symbol will be available in this.persist.