I think it is in part laziness. They understand that Car PCs are not well known. So to someone like my Mom or Dad or people not into the hobby, they wouldn't know or understand that there is a better solution to what Hyundai did. They will simply think, oh look that car has a Mac in it, but no other car here does, so that must make it better. They would probably be even more shocked if they saw any of our cars. I guarantee most of the Mp3Car Forum members make that setup look like cr@p. On the other note, maybe Hyundai does know that there is a better solution but they don't have the personal, time or money to invest in a pure integrated system. In a few years car companies will have no choice but to start integrating, especially when they see that people are holding onto their cars and installing better equipment then the new cars their rolling off the assembly line (no profits).
PS: why does the Genesis look so similar to the BMW 5 series? Hyundai loves coping other car companies!