I think it was a promotional gimic to sell more cars. To atract those who wanted something a little more sporty. Special colors and graphics and it is still working today.
Grabber was 70 only for the Mustang. Appearance package there too. The 'Grabber' colors used different names in different years/models. Same colors, different names... Appearance package, sales gimmick. The hood and spoiler were the best things to come out of the program IMO.