$ aptitude why plasma-runner-telepathy-contact
i plasma-runner-telepathy-contact Recommends kde-telepathy
i A kde-telepathy Depends plasma-runner-telepathy-contact (>= 15.08.3)

I wonder…
Seems wrong.

Recommends != Depends.
It looks like it is saying that if you install the plasma-runner-telepathy-contact package that you really should make sure to have the whole kde-telepathy application, including the rest of the packages that are part of kde-telepathy.

I would guess that there are many applications which are similarly bundled in groups of packages, where there is a top-level package which depends on all of the sub-packages that are required for that application to work, and that each sub-package recommends the top-level package to encourage users to install the whole application instead of just individual parts which may not work properly by themselves.

I agree with Your view of things.

My remark is not a fundamental criticism
concerning the package distributors.

We have "requires", "recommends", and "suggests"
dependencies. The packaging system can be configured
to treat "requires" and "recommends" the same.

This could lead to great blocks of uninstallings if
You later decide to uninstall a single component.

This could cause problems for inexperienced users
in the end.

I've read the definitions of all 3 kinds of dependency
in Debian's packaging-guidelines.

I somehow think that the dependencies should be the other way
around:

plasma-runner-telepathy Depends …
kde-telepathy Recommends …

I still wonder. But thank You for answering.

Maybe I'm wrong.

kde-telepathy is a metapackage, who's existence is created purely to cause a set of pre-defined packages to be installed. It contains no actual software itself. This one pulls in all the individual components that make up the KDE Telepathy system. If you remove a bit you don't need or want, say plasma-runner-telepathy-contact, if the metpackage kde-telepathy is not removed as well, the system will always want to reinstall plasma-runner-telepathy-contact as i] kde-telepathy[/i]'s existence would keep pulling the unwanted package back in.

Removing a metapackage does not necessarily mean that all the components will be removed as well.

Yes, the dependency looks weird and is confusing, but it seems to work, usually But afaik it is correct.

@claydoh

You are right.

I didn't realize that the package is

Architecture: all

and only contains 2 text-files:

/usr/share/doc/kde-telepathy/copyright
/usr/share/doc/kde-telepathy/changelog.gz

Problem solved. Thanks.