Let's not forget that the current ES was originally designed before 2007--6 or more years ago. That's when the decisions were made at Toyota as to which systems would be included in the vehicle. I'm not at all surprised that your 2011 NAV system works the same as the one in your old 2008 Camry, as they are likely identical. Since the 2012 Camry is a redesigned version (a new generation?), I wonder if Toyota bothered to upgrade the NAV system with some new technology? Anyone seen the NAV in the new Camry, as that's likely to be the system that is in the next gen ES.
Also, with the world's economy still in the tank, car manufacturers will do virtually anything to save money (improve profit), and keeping some technology bits around longer than they should is surely saving them money. Both Honda & Toyota have made a science of "de-contenting" their vehicles, which can help explain why some systems/parts are kept in production waaaaay longer than we owners think they should be.
I believe all 2007-09 ES Nav systems are DVD based. The whole car does not need to be re designed in order to upgrade (or fix) the Nav system. Just a new DVD.