To make the old Megalopolis environment card "Targeting Innocents" go away, you had to do 5 or more damage to the villain in a single round to destroy the card. From the PDF of changes made to EE cards, it looks like the card now has 10 hp so you have to do that much to the card itself to make it go away. What exactly are we shooting, when we're shooting the card to make it go away, do we think?
I view it as a sort of "suppression fire." Essentially making the villain keep his/her/its head down while the innocents can escape or be rescued.
I really like imprimis5's idea!
I thought it was stopping the forces of the villain from targeting the city's innocents. For example - per the art and flavor text - the heroes would have to destroy the artillery ships if the villain is Voss.