[ape4]

If that happened browsers would have to make "html:" optional. So authors could get away without using it.

[jayrox]

and at that point a complete waste of being in the spec to start with.

[xienze]

Err, no. XML allows you to set the root namespace for an element so it and child elements have an assumed namespace.

The point of using namespaces is to allow embedding different document/element types in the same document.