ok, my personal view from my experience as dotnetnuke user, project lead and core team member:
IMHO the modules and associated projects are a necessity for DotNetNuke, because
- a framework w/o packaged modules, demonstrating its power and options become unattractive
- as I understand, the selection of bundled modules shall cover basic common needs of web sites. This is, where new modules like a membership directory, map and chat were selected to be developed and get bundled in the future
- the new release tracking process shall guarantee, that the modules can be trusted and work as "best practices". (There is of cause a downside, that this testing slows down the release process and binds core team resources, but IMO the result makes it woth this)
- new features of the core needs to be demonstrated and tested for their practical value; in the past, there have been always some of the modules jumping up very fast on the train
- the need of module teams are also a valid source for extensions or modifications of the framework. e.g. problems of modules with the URLcontrol led into improvements in the past releases.
- we are also working on identifying features from the projects, that would have a benefit for many other modules and move them to the core framework. This started recently, but I expect a number of enhancements moved in the future
- projects are a test ground for new core team members. most of the newly recruited members have been team leads before
The current selection of modules demonstrate different developement approaces (DNN3, WSP and WAP) and different levels of complexity - starting with simple Text/HTML up to complex Forums, Store and Repository. This allows each developer to start his own modules by looking at a core module of adequate level.
PS: John, AFAIK there are no plans to retire core modules and never had in the past. Some are no longer bundled with the core, as they currently don't meet the quality standard and some modules as not under continuos developement due to a missing team (while we are on search of a new one) - and please, always keep in mind that all project teams are run voluntarily. In fact, there have been only two modules retired yet, because they had been superceeded by other modules: Discussions (now Forums) and Contacts (replaceable with more flexible UDT).
As stated in the first line, this is my personal view, not an official position of the core team and DotNetNuke Corp.