What you propose is rewriting GladeXML but using perl instead of xml for interface description.

I fail to see what's the advantage of writing

          <child>
            <widget class="GtkTextView" id="text1">
              <property name="visible">True</property>
              <property name="can_focus">True</property>
              <property name="editable">True</property>
              <property name="justification">GTK_JUSTIFY_LEFT</propert
+y>
              <property name="wrap_mode">GTK_WRAP_WORD</property>
              <property name="cursor_visible">True</property>
            </widget>
          </child>
[download]

instead

$parent->TextView(
    Name => "text1",
    -visible => 1,
    -editable => 1,
    -justification => "left",
    -wrap_mode => "word",
    -cursor_visible => 1,
);
[download]

And where are those tools that would allow drawing GUI with your proprietary perl interface?

Tcl/Tk was written to make it easy to write GUIs with just a text editor, and Perl/Tk is comparable. Some people may not be comfortable with this approach, but some are.