The flying car, as it could be made with today's technology, is just a novel alternative to a helicopter, as you point out (or perhaps a "roadable aircraft"). They'll suffer from all the same problems of the aircraft that people aren't already using, including the cost to own and run one.
But most people don't think of it that way. Most people think of the flying car as a poorly thought out idea from a cartoon. It'll be just like a regular car except you can get away from traffic by moving up or down! It would solve the problem of traffic congestion!
Unfortunately this idea is so far from attainable with today's technology that nobody alive today will live to see it. They'll need Star Trek batteries to carry a large amount of affordable power running affordable motors, first and foremost. The average person is already struggling to buy and run a small number of relatively very pedestrian combustion engines, they can't afford anything that has multiple exotic forms of the damn things ferociously guzzling precious fuel.