>>92775941out-of-universe, its inspire by the GIR hoodies that were all the rag with hot topic goths
in-universe, I think Flugg was trying to make a mini-kaiju super soldier but instead of an upright monstrous reptile he got a mostly normal looking girl (other than her one slitted eye and weird hair) with reptile powers. the hoodie, then, was likely his attempt to make her look more monstrous when presenting her to Black Hat, who was not fooled and declared her faulty merchandise so shut down that avenue of enterprise.
