I found the origin of this change to be the following commit:
https://src.fedoraproject.org/rpms/kernel/c/b65f9ed036fca30c0684bfc6fe72d...
(which is a revert of a revert to remove the kernel-doc subpackage).
The commit also suggest that the package might be a candidate for a separate SRPM which
would maybe result in it not needing to be build everyday? Also if I understand you
correctly I assume that some of the hacks to koji are not needed anymore.
Due to this and given that RHEL includes it I think I will do as suggested and file a bug
report.
Thanks for your responses.