First, I’d like to say that I am very happy with Radiant as is.
It could be a little simpler than as it is now. I belive that we can
delete from the source add a little, drop some models and tables and
have more functionality.
Pages can have parts and children. Why both? Parts can contain text and
children can too. I could live without parts, I need only a body in
Page.
PageParts:
In /main Instead of
<r:content part=“extended” /> one could
<r:find url="/main/extended"><r:content/></r:find>
Snippets:
Instead of <r:snippet name=“header” /> one could
<r:find url="/snippet/header"><r:content/></r:find>
Snippets can have structure after the mod, is it so bad?
Layouts:
Each page has an attribute layout, but that’s can be just a page. I do
like simplicity but some not. They can have their layout specify yet
another layout.
The unified resource locator should be able to target my created
resources. Right now url can not target a page part or snippet, so my
ssi-cache is defeated because it just can’t include in a dynamic part,
it has no url. Also when I do ajax magic I have to defeat page’s
rendering not to do layout.
Some day some will say: I can’t live without reordering / reparenting my
page parts. Then what. Well we code that too, or let the parts go and
page-reordering / reparenting is almost? done.
The extension mechanism is very promising. I think this is all just an
extension. Some can like it, some not. No hard choices here. Some tags
needs to be reimplemented, some (reversible 
migration, that’s it.
I wonder what was the design consideration behind not to use pages for
all of this. If there is an answer, point me to it.
Laszlo