ABNF srgs

http://www.ietf.org/internet-drafts/draft-porter-srgs-media-reg-01.txt

I'm not sure than I'm opposed to this I-D, though it is certainly
unusual for a non-XML MIME type to heavily reference RFC 3023.  However,
could you please explain the reasoning behind encoding the same
on-the-wire grammar with two different (but cross-convertible) syntaxes:
ABNF and XML?

It seems like a huge amount of work for little or no gain.  Certainly in
the context of MIME, there is much better experience in transporting XML
documents (and dealing with related i18n and encoding issues) than the
ABNF grammars that this I-D registers.  Plus, to quote RFC 1958,
Architectural Principles of the Internet, Section 3.2:

  "If there are several ways of doing the same thing, choose one."

I assume this has been thoroughly debated but I cannot find the thread
at <http://lists.w3.org/Archives/Public/www-voice/>.  I see at
<http://www.w3.org/TR/voice-intro/#gram>:  "We anticipate that
development tools will be constructed that provide the familiar ABNF
format to developers, and enable XML software to manipulate the XML
grammar format."  I can understand that developers find ABNF easier to
read and write.

However, is it really necessary for the ABNF format to be released into
the wild (i.e., sent over MIME protocols)?  Wouldn't it improve
simplicity and interoperability to say that ABNF MUST first be converted
to XML before transport?  More strongly, wouldn't the document be more
clear, straightforward and interoperable to say that XML is the