Namespaces were added to RSS by Dave Winer in fall 2002, at a time
when the next version was going to be numbered RSS 0.94. (It was
renumbered RSS 2.0 at first publication.)

http://www.rssboard.org/rss-2-0

His intent in doing this was described in a Scripting News weblog post:

http://www.scripting.com/2002/09/06.html#When:10:56:56AM

"I've added the section explaining how to extend RSS through
namespaces. I'm basically telling you to ask the W3C how namespaces
work, and do it the way they tell you to do it. I don't want to assume
the problem of documenting namespaces in the RSS spec. Then I modified
the roadmap, it got a lot simpler. No more innovation. RSS is frozen.
Only minor adjustments are contemplated."

At the same time, he described his interpretation of the RSS 2.0 roadmap:

http://www.scripting.com/2002/09/06.html#theRoadToRss20

"Namespace support is no longer in the future, the core of RSS is
frozen, no features are deprecated (explain why), there may be a 2.01
and 2.02, for the purpose of clarification, but no new core elements
are anticipated."

This tells us a couple of things:

1. The author of RSS 2.0 had no intent to include namespace elements
while excluding namespace attributes. His intent was to defer entirely
to the XML in Namespaces specification.

2. He also anticipated future versions of RSS 2.0 for "minor
adjustments" and "for the purpose of clarification" but did not want
new core elements to be added.