[It was a plane constructed around a cannon.]
It wasn’t a total waste. These assessments are all relative to what the opposition puts up. Against a mounted knight kitted out with the best armor money could buy, the Airacobra might as well have been the Death Star zapping an entire planet in Star Wars. Vs the USAF’s actual opponents, it was a death trap. Another dog of a plane (this time a Navy aircraft) that shone when used in less challenging environments - ironically by the Finns against the Russians - was the Brewster Buffalo:
https://en.wikipedia.org/wiki/Brewster_F2A_Buffalo#Finland