I rather think Douglas is somewhat confusing between research and product.
Plan 9 is a research oriented project, and hence, we don't expect 'compatibility'
to the older standards.  The purpose of research is destroying that older
concepts.  :-)  Then, I think it's enough to ask designers why you do so,
when we feel something is missing in Plan 9.  Then, if you don't like it,
you can start another project by yourself...

Kenji