It would be very helpful to be able to have access to a file containing all the V2 Elements standard properties definitions so that Custom Components would follow the V2 guidelines.
This file could be downloaded and edited to remove the properties not required by the Custom Component; it would help speed things up on the developer front. 
This is something I have been meaning to raise as well.
The problem with most of the third-party components at the moment is they all lack the standard set of properties common to most of the Elements components. This largely makes them unusable without wrapping them in an Elements component in order to gain access to those properties.
I agree that having a template component with all of the common properties would be a great way to set some sort of standard for the development of custom components. I know for myself if this was available I would be creating my own components.
Not only that it serves as an example of how to correctly follow the guidelines for creating a component.
Any chance of seeing something like this?
Great idea, this would make thinks a lot easier for those of us that are not the best coders in the world. 