In my opinion in his previous post Robert Collins proposes a change which does not help packaging, instead it would just make things worse.
DO NOT include a packaging debian/ directory into your source tree. If for whatever reason you need to provide your application out of the official repositories just upload to a PPA using the regular process with the source+debian diff .
Including the debian directory on your source does not help anyone, however it will make life's harder for people that wants to package your software. The debian/* format is standard but it's implementation, integration and component versions between different distributions and releases are not.
There are plenty of reasons for projects/individuals to provide your software built/integrated in a different manner. Including a specific version of a package building process on the source will conflict with the regular packaging process, source+buldif diff forcing other packages to change your source by removing the /debian dir or maintaining a diff for it.
I agree with Robert that upstreams should be more involved with distros and whenever possible take care of the packaging, the blockers for that are more social than technical. If there is an understanding that the "introduce a new package" process is not acceptable/friendly with upstreams then it should be improved.
If the objective was to improve packaging collaboration then just move debian/* to a VCS, that way everyone can collaborate: upstream, distribution maintainers and 3rd parties.