My reasoning may be flawed, but I would think that any state that voted for Obama would not need to use the VRA to create African American majority-minority districts because white racists in the state are obviously outweighed by people willing to vote for a black president.
Well Obama didn't win any of the states that are fully required to obtain preclearance for redistricting except Virginia (Florida only requires preclearance for part of the state). And considering their reactionary state legislature just attempted to gerrymander its electoral vote apportionment, I'm not sure we can trust them to their own devices.
One thing I've never understood is why Arizona is required to pre-clear. There are barely any black people there to disenfranchise, and there certainly weren't any when the law was passed. Was there some sort of discrimination against Hispanics going on there?