On what flying cars can be good for
The number one danger for small aircraft is when people fly in bad weather. It usually happens when the weather goes wrong between airports. They crash while struggling to get to an airport to land. If you can land anywhere in between, with impunity, then you're more likely to do it.
A lot of pilots don't like to land on a highway, because they'll end up spending the rest of their life giving urine samples and explaining to CNN and the police department why they set down on a street. But the fact is sometimes that's the right thing to do. Having the ability to land and drive away in a storm can help. Also, driving from an airport that has bad weather to one that's clear and less windy or foggy to take off … there's a lot of value in that for pilots.
As for ground travel, traffic is often very congested and getting worse. Sometimes the best path is not to take a street, maybe there's a better path through the air. There's a value for both.