reason for kross being a kdepim-runtime dependency

[Matthew Millar]

Is anyone able to advise of the reason for a core kdepim package to require 
kross?

I would have expected user-level applications, such as kmail to have this 
dependency in the case of implementing scripting features, such as e-mail 
rules. But can anyone advise of the reason for it's mandatory requirement for 
kdepim-runtime?

Many thanks