As someone who knows rather a lot about HyperCard: it was never allowed or positioned to fulfill its potential. There were easily fixable security issues ruining the opportunity to be the center of OS scripting. The UI was never rewritten for color and to match the Mac UI, which would not have been complicated either. The code must have been very difficult to upgrade, either technically or organizationally, because the entire upgrade run past 2.0 was so meager. It was a piece of genius, but in the end, only a piece.