The narrative pivot just happened to fit well with their overall rebellion against established shounen tropes and archetypes. It’s what makes it so enthralling. Something they have thankfully kept in the remakes. It’s a shounen only superficially, it has all the flashy action bits and colorful high tech things, the blank MC, and the harem cast. But then you get to the characterization and dialogue and it’s pure existentialism horror.
I’ve read it both ways with sources. Read also a third that they never had the whole budget to begin with and overextended due to clerical error. Alledgelly the latest remake has the style of ending they originally envisioned with lots of fight sequences and more experimental animation. It’s part of the endless debate.