Try to be positive in what you say. i.e. don't just criticise the present systems but suggest how they can be improved.
e.g. "While I fully understand that the rules relating to XYZ are there to ensure client confidentiality and business transparency, I believe that those objectives could still be met by doing XYZ in the way that I'm going to suggest, while at the same time reducing the workload for staff, through simplifying our systems. That would result in greater efficiency and reduce the frustrations which I, and my colleagues, often experience through having to do XYZ by the current methods"