I think that these days, the best large banks do not view software development as a cost center anymore. I'm hearing more and more from people in banking that banks these days are basically IT companies with added security constraints.
Mandatory developments, impositions of central banks, national vat's, auditings and bussiness as usual is seen as a cost. You must do this developments. These are fixed costs and banks tend to minimize them.
New products that inovate/diferentiate one bank from another are seen as strategic and costs are seen diferently. What banks optimize in the fixed costs, banks spend in the proof of concepts.