My question: Is it possible for wing development to be limited in favour of ground effects? Can ground effects replace the downforce lost from less complex wings? Would it be cheaper?
A proper ground effects car could easily out-perform a winged car. More downforce could be generated, but just as important, it would come with a lot less drag. In fact, if you examine picture of cars from the ground effects era, they didn't really have wings, they were there just to trim the aerodynamic balance.
"Cheaper" is a relative term because costs are not driven as much by the level of technology but rather the team's needs to develop some part. For example just ten years ago front wings were very simple devices. But today's are complex in shape and manufacture, making them expensive to build, and develop. The change in regulations making the front wings narrower has changed the way the air flows past the front wheels and over the rest of the car, making front wings a critical development item for any team.