Jeffrey had a good question.
Suppose the home page of my site is a blogHome page.
Now I want to have an index on one of the lower-level pages.
There was no way to do this. Either the top page is an index, or none of the pages are.
This is obviously not a good thing.
Now, if you set the type of any page to index it will render as an index page.
You don't have to supply an index type template, because at the same time I added a bit of code that says that if a page has a type for which there is no template, use the outline template. This solves a bunch of other problems too, and can't result in breakage (something I'm starting to worry about) because there were no pages that rendered without a template previously.
I also changed the defaults for index pages so that the stories and dates would be off by default. These features were there in a vain effort to get the index type to do what blogHome type does. Now that we're not trying to do that, it made sense for the defaults to be set up for the simple case.