Times when usability cannot improve an interface

Yes, with all the knowledge of user centered design, there are times when usability process cannot improve an interface. Usually this occurs when the business process (read features) of an application, software or a product itself is so convoluted that usability ( though one may try their best ), it may not improve an interface.

These are situations when its best to re- engineer the business process at the start of the user centered design process. Does it mean that usability professionals should be management consultants as well? The answer to this is yes and no. This should be a collaborative process where the usability expert can bring their expertise early and often in the process. Previous knowledge about the vertical helps and its good to develop pool of resources for a particular vertical.