It was gimmicky from the beginning, because all (as far as I know) First Federal branches were built in the same shape. As if there were no other way to know you were at a 1st Federal branch. I worked in that building for a time, and it was a bit toward the claustrophobic, especially compared to American Federal-now-Prisma, which was (still is?) open and spacious.
Idle speculation, but I wonder if they did go for a gutting, if you could cost-effectively build the "missing" superstructure to make it rectangular? Truist across from Haywood Mall is one of those buildings, whose shape has been corrected (note the mismatched brick). But that's just one floor, of course.