No one along the line really cared, and consumer feedback hasn't been strong enough to force a change would be my guess.
Ford recently sent out USB thumb drives to all of their customers with a newer Sync enabled car with an upgrade on it. They did this because their overall car satisfaction ratings were taking a hit due to how bad the new system was. They wanted to get the changes out quickly instead of having people do it manually, or waiting till their next service appointment.
In car entertainment is still an area that could use a lot of improvement. We here all were spoiled with such a great product in 1999. My experience with the CarPC showed me that even the enthusiast market isn't really in it to make something great.