Problems with output - "The row plugin is not of type Unformatted."

Got it. The problem is the "Unformatted" row style is only presented by the Views JSON module (which I did not install) but the Views XML and Views RDF modules effectively depend on it.

It's not really a "bug", but the .info file ought to make it so you have to install the module containing the style plug-ins. =)

or at least break out the core common functions separately and make that a dependency

That makes the most sense. =)

No it isn't - it's a lack of dependency in the info file. The whole reason the dependencies array exists is so you can prevent this from happening. Not implementing it properly is a Code Bug, not a Documentation Feature Request.

I think if you can get it to work the way you describe, it's lucky rather than anything else. I say that because if you look at the views_xml.views.inc you will see there is no Unformatted plugin. Conversely, if you look at views_json.views.inc you can see the Unformatted plugin there, second one in the views_json_views_plugins() function. So there is clearly an un-registered dependency, as previously noted. It needs to be fixed by either:

- making the other modules depend on the JSON one, which contains the plugin
- including the plugin in all modules so they don't depend on JSON because they have their own copy

So you can see, when you read the actual code of the module, this is clearly a bug as originally described. You might have found a workaround, but the bug stands. It's literally there in black and white. ;-)