A material on an image could just work as if you have the PositionAsUV1 script, without having to add the script. If necessary, toggle the functionality with a checkbox on the image component. This would be much more discoverable. Also, the naming doesn’t make much sense - position what as UV1? the entire object?
Canvas space position.
There is an overhead of setting this, and you may want to do something else with UV1, so we don’t want to integrate it into graphic.
What is PositionAsUV1 for?
It’s for custom shaders that want to do specialised effects based on the vertex’s canvas-space position.
Any examples of effects that can be achieved with this?
Screen space refraction for elements behind the UI is the primary use case 
Can I get a sample code?