I'm not sure URLs have any major downsides. The full complexity is beyond most people but most people don't need to understand anything more than how to type www.something.com, it is the web application owner who has to understand them and where most security problems live. Security is only a problem if the server or web application have not been setup correctly.

It's no different than visiting a shop or a house where you should be able to expect certain regulations to be met (insurance, building codes etc) and I can see more countries starting to enforce country-wide codes for web sites, annual checks, registrations, whatever for people to be allowed to trade in that country.