I'm not sure whether this an answer, but it is too much for a comment and more than just an edit to the question.
I have tested on two systems, with
- Visual Studio Community 2017, Version 15.1
- Visual Studio Professional 2017, Version 15.3.2
and I believe that the functionality has changed between these two versions. I think it is unlikely to be a difference between the Community and Professional versions.
In both cases I created a new ATL project and tried three ways to add a class:
- Add class... from the context menu in the Class View
- Add class... from the context menu in the Solution Explorer
- Add New Item... from the context menu in the Solution Explorer
With version 15.1, Add Class opens the following dialog, from which I can add an ATL Simple Object.
With version 15.3.2, Add Class opens the following dialog, without any option for an ATL Simple Object.
However, with version 15.3.2, Add New Item opens the following dialog, with a new option to create an ATL Simple Object, which was previously not available in this dialog.
So, it seems that the functionality has been moved. Curiously, it is no longer available in the Class View (which in my opinion is a mistake).