The new "form" element can also be useful within an host language, such as HTML, to contain all models and controls.
When a custom control is to be executed in a standalone form written in HTML, the "form" element could be anywhere within the body part. It could, then, be easily extracted from the standalone form to be executed within the embedding form, without title, header, footer...
It could also be useful for authors having to mix XForms with, for example, some Javascript framework used for rendering navigation.
It would, then, be similar to HTML "form" element.
Regards,
--Alain