"It showed them how far the upper stage could get almost to Ceres,"
If they didn't do the PR stunt of trying to land the boosters, they could have made it to Ceres. If they were really clever, they might have been able to land the car on Ceres. That would have shown more acumen than just flinging the rocket up as far as they could make it go. A photo of the roadster on the surface of Ceres would be serious space cred.