The Debian packaging of Koha does not include translations. It should include translations at least for all the languages that are 50+% translated. Since OPAC users (especially) may be wanting to use their own language, the translations should be included in the koha-common.deb package.
I also vote for including translations. It would have to be separate packages for each language. First, would there have been only localized interface templates. And later would have to add other language-dependent things (eg., language-patches, settings etc). Now after installing the package koha or koha-common in the web-installer is not possible to select other languages and therefore can not choose a language-dependent sql-data (although they are currently in issue).
Yeah, separate packages is how I'm intending to go with this, that way it'll work similar to localisations for other packages (e.g. firefox has something like firefox-locale-nl etc.)
Translations are shipped with Koha these days, and there are a lot of them. I'm not planning to create a gazillion Debian packages for them.