There's a discussion over on an XML list
about format bloatation.

Here's a link to one of Dave's contributions
to that discussion:

http://lists.w3.org/Archives/Public/xml-dist-app/2002Jan/0094.html

I think he's nailed it.

Text formats surf nimbly
in the giant wake of multimedia files.

Just as apps can be written in Java or
scripting languages like UserTalk and
still have quite acceptable performance
on our hundreds-of-megahertz megs-o-RAM
honkin'21st-century muhcheenz.

Here's some data on file sizes on a
50,000-node outline stored in text, OPML, and MS-Word
format (woulda had a PDF file, but my tool
choked on even a 2,000-node outline):

http://JavaOutlineEditor.org/OPML/Derby/File_Size_Bloatational_Data.gif
http://JavaOutlineEditor.org/OPML/Derby/File_Size_Bloatational_Data.xls

stan