The decision was taken in 2003. At that time LockMart thought that they were on the good side of the weight issue (they were thinking of modding the -35B to carry 2K JDAMS). The problem was the life-cycle cost of the gun, including the support of a completely new ammunition family - it was concluded that the GAU-22/A would be less expensive. And that's how the -35A ended up with the horrible wart above the left inlet.