As the debian maintainer of icu, I would like to request removal of the debian directory from ICU's sources. I actually made this request some time ago in a private email discussion with George Rhoten, but I'll do so again in the tracking system. I'll outline my reasoning.
When I build debian packages for icu, I specifically ignore the debian directory in the package. For one thing, it is not kept up to date. For another thing, every debian-based distribution may potentially have to modify it, and such modifications are, by their nature, not going to be suitable for inclusion "upstream". Since I have to modify debian/changelog and other files with every new release, the debian directory in the ICU sources will always be behind the actual version in the debian package. In fact, since the names of libraries and so forth change, the debian directory that is there in the ICU sources won't even work for an end user who wants to build the packages. Changing these is something that falls to the debian maintainer. It would be a waste of time on the part of the ICU maintainers to try to do this.
Rather than having incorrect debian directories, I think it would be better not to have any at all. The debian directory is part of the "debianization" of a package, and should rightly live in the debian archive and not in the upstream package. Even for my own open source packages, one of which is officially in debian, I keep the debian directory separate from the upstream sources. I control my debian directories in a separate subversion repository, and should I eventually turn over maintenance of the packages to someone else, I would turn those over as well. The history of the debian directories in the upstream sources doesn't reflect reality, though they have been synchronized from time to time.
The only reason I could think of to have a debian director in the ICU sources would be if that directory actually made it possible for someone to download ICU and build their own debian packages. This would require that someone one the ICU development team tested the debian directories to make sure the packaging is correct. Additionally, since the ICU packages in debian have been in good shape and staying as current as allowable by debian's own release schedule, there is less reason for anyone to need to do this. I communicate any bugs posted to the debian packages with the ICU developers, and I also monitor the health of ICU in Ubuntu to make sure my ICU packages will work for both distributions.
Should I eventually become less diligent in my maintainer duties (unlikely) or should I eventually hand this off to someone else who does a worse job in keeping things up to date, then maybe it would make sense to consider inclusion of debian directories in the ICU sources once again.
In any case, this is just a request. It doesn't really matter that much to me since I systematically ignore the debian directories in the upstream sources. I just think it's misleading to people who download the packages to find debian directories that are out of date and don't work.
Thanks for your consideration.