The causes are multiple. Patchwork IT landscapes built up over years of M&A, products that require servicing for decades and all set against a backdrop of continually changing regulation. The result is a complex web of technology and processes which few people understand or can explain. Attempting radical change in this kind of environment is perilous.
The only substantive solution is to build robust models of a business to enable discrete components to be isolated, managed, measured and improved. Without these models, change will always be a lottery. With them, it becomes possible to determine, design and deliver specific business and technology change that leads to vastly more efficient operations.