Generally engineers don't make dumb decisions, there are exceptions, they make plenty of hard ones. The difference between the Thompson M1928 and the M1A1 isn'

Generally engineers don't make dumb decisions, there are exceptions, they make plenty of hard ones. The difference between the Thompson M1928 and the M1A1 isn't that the M1A1 is superior, and yet they cranked the handle on the latter as hard as they could during the war. So "If something were better than something else, why did they make more something else during WWII?" doesn't persuade me. Nor does it eliminate other arguments which would make sense.