CCK was born as the little brother of MCD in the 4.04 release of Communicator. (MCD is Mission Control Desktop - a set of tools aimed at enterprise control of Communicator on the desktop.) As such, CCK had to satisfy the demands of its target audience by simply making customization and distribution even possible.
The dialup component from the Navigator/Communicator Retail product is also included in CCK. Since CCK's focus has been primarily for ISPs and secondarily for other distributors, the dialup component has been necessary for its success.
In the 4.x releases, we attempted to "eat our own dogfood" as much as possible, so several of the tools were written using a combination of technologies introduced in the 4.x Communicator. Account Setup, Account Setup Editor, and Config Editor were all written using HTML, CSS, Layers, Javascript, LiveConnect, Java, Java Native Methods, Plugins, Security Layer, Signing, and other new stuff. While this was cool and interesting, it was also somewhat painful since the technology moved a lot faster than we could keep up with.
The results of that effort are available from mozilla.org via CVS by checking out the mozilla/cmd/dialup directory. The old Mac version is out there, but probably has problems since we had to hold back some stuff that wasn't legal to share and that seems to have broken things.
Along the way, the importance of distribution wasn't felt equally by all parts of our organization and the team working on these tools was made to shrink. We lost the ability to sustain the Mac platform and and also Win3.1. Hence our current situation where we've had to focus on getting a Win32 set of tools out quickly with a small number of people. (We could really use your help if you've read this far and you're interested in the Mac :-)
On the plus side, we're now totally focused on the CCK market and building tools explicitly for the needs of that market.