Economics must have had a hand, after all economics and safety can't be separated in most fields.
When Concorde was withdrawn from service it has to be remembered that post Sept 11th the whole aviation business had taken one of its downturns and the general economic situation had led companies to re-examine their corporate travel budgets.
I remember being told by BA's then Concorde chief pilot that BA used to have nearly 20 companies who specified Concorde travel for their executives where available. Prior to its permanent withdrawal from service that number had become zero.