Hi,
WebResources folder only has components of type WebResource. There are 10 types of WebResource defined in CRM and these are the only WebResource supported by CRM. Check out the New WebResource window, it has Type drop down.
Though a CRM solution has other components like, Entity, Processes, Email Templates, Security Roles, etc. They are not Web Resources, hence they are part of WebResource folder of a Managed Solution. This is the default behavior of CRM
Hope this helps.
Ajay Chawla