A simple point. Many MOSS pages come out without WCM features. For example even on a MOSS site a new Team Site has only the features of WSS.
So can you apply WCM descipline and desgin features to a team site? Yes. Just go to site settings and bring up the site features. Web Content Management and Publish will be disabled so just activate it and even a team site will now have full WCM features.
If SharePoint WCM features are what you need for a task is another issue. If you have used almost any other WCM product be warned, MOSS WCM will not have the same features. Still its a major step up from SPS 2003.