Plug-in data sources (described here: ArcObjects 10 .NET SDK Help ) are a useful feature that allow ArcMap users to read data from custom file formats without importing them. However, the current development process of Plug-in data sources still involves a relatively complex deployment step that requires an installer project to be created. Installers create a barrier in some organizations if system administrators are the only ones allowed to run installers.
Add-ins allows developers to extend functionality of ArcGIS without the use of the registery (as far as I can tell) and without the need to create installer projects. I can implement interfaces like Buttons and Extensions, why not plug-in workspace factorys? Could Plug-in Data Sources be implemented as Add-Ins?