Also the commitment of resources and user interaction research and development consequences of user behaviour, I'm sure weren't decisions made by whoever prover

Also the commitment of resources and user interaction research and development consequences of user behaviour, I'm sure weren't decisions made by whoever proverbially "slaps on the last button at the bottom of the screen ". I would be fascinated to learn about how the effects of such a interface change are studied. Edit to clarify my inquisitive interest is in the Who Moved My Cheese effect on subsequent purchases after a long loyal customer has been made aware of the possibility of their most important attributes of the product which they're buying and paying a premium for, aren't guaranteed to continue to be available at all. If the most frequently used interface is up for unexpected total disruption, what is the effect that has upon the long term purchase plans of previously loyal customers?