Indy Car configuration.?

I'm sitting here watching the Indy Car race from Detroit. I have watched the configuration of these cars for the past couple of years. First they put aerodynamic covers around the rear wheels until they're almost completely enclosed. Now, I see the front wing has been changed until it almost hides the front wheels.

Why doesn't Indy Car racing just slap fenders (front and rear) on the cars and admit they've given up on open wheel racing.