John
I suspect the demand is overrated and many workflows don't 'need' click-and-do functionality, for example. I imagine it differentiating the need versus nice functionality. Even their click-and-drag example, I find a bit slim, since I would want to have full control over the area of interest bounds. I can seem situations where it might not be critical or important, but is it just convenient or a necessity.
The documentation in the link makes an attempt to explain this, but I still see the desire by some to go this route as a first go at creating tools rather than something to work towards based on no other recourse in their workflow. It would be nice if one example was chosen/produced and options presented in the help files or in a developer document somewhere.
What is a Python add-in?—Help | ArcGIS for Desktop
If it is required to make a customization that performs an action in response to an event, or requires the use of the mouse to interact with the display, you should consider making an add-in. An example is a tool that requires the user to click and drag a rectangle over a map to define an area of interest. Another example is an application extension that saves the map document automatically anytime a layer is added or removed from the table of contents.
