Its not that it was just a difficult bug. Its that politics got in the way of doing the right thing, which is declare the airplane "new" and re-train the pilot

Its not that it was just a difficult bug. Its that politics got in the way of doing the right thing, which is declare the airplane "new" and re-train the pilots (vs a plain modification). Boeing didn't want to do that as customers didn't want the retraining expense so they used lobbying and cut the corner.