Percentage-based fees are rarely appropriate, imo; for those paying the fee, naturally. It's a phenomenon that we simple seem to take for granted. I believe that any system where fees are based on percentages is ripe for disruption. I include this particular case, credit card transaction fees for merchants, ebay, estate agent/realtor fees and so on.

Of course, where the market is closed/protected, then the only way to change it is to lobby politically. And good luck with that in the banking domain.