Currently the kcmshell5 executable is in the kde-cli-tools repository and depends on plasma-workspace. To avoid a dependency to that project apps like kwin or kdeconnect have their own kcmshell implementation.
My suggestion would be to move kcmshell under the name kcmshell6 into the kcmutils project and thus avoid having multiple implementations of the same utility.
This could be done when KF6 is branched, without having to worry about conflicting names.