the problem of unregistered MIME types, URI schemes, etc.

On the "happiana" mailing list, I was trying to make the claim that the widespread use of unregistered MIME types was a security and reliability problem in the web... that whenever there's a potential for a disagreement about what a communication term means  -- where the sender intends one thing and the receiver understands another, and they're both (more or less conforming) --  that this is a priority for us to fix.

(see the thread starting http://www.ietf.org/mail-archive/web/happiana/current/msg00016.html for example)

Some of the pushback has been that this is not a reliability problem, that the fix for the problem is not in the IANA registration process or anything maintainable by the IETF, and a few other things ....

The conclusion I reach is that the problem of getting existing types registered isn't going to happen in IETF, that it is a "web reliability" problem...

Having widespread use of unregistered types, URI schemes, etc. labels is harmful, and that if the "fix" is something beyond what IETF and IANA provide, that perhaps W3C could provide some resources to help.

Do you agree or disagree with this analysis or direction?
I think part of the issue is whether new URI scheme registrations should be encouraged - even if you don't like inventing new URI schemes....

Larry