Want to know how screwed the score system is?
(Edited, I originally outlined an easy way to lower attack/bomber rank here but I don't want to encourage that sort of lame gameplay so it's gone.)
I know you're talking about perks not rank, but the point is that 1 bomb and silly strafing of multiple targets is worth "more" score, perks, rank, whatever, to the game than any sort of "strategically useful" (as pragmatically defined by game mechanics) bombing. So don't worry about it, you did nothing wrong.