Oscar: Hepburn Losing the Oscar to Ginger Rogers???

Ideally, the selection of Oscar winners should be determined by two factors: the quality of achievement and the intensity of competition in a given year.
 If logic or reason dictates, there should be a strong correlation between the intensity of competition and the quality of the Oscar achievements. In actuality, however, in years of fierce contest, the winning performance is not necessarily the strongest; at times, it is the weakest.
In 1940, the competition in the two lead acting categories was particularly intense. The nominees for Best Actress were: Bette Davis in The Letter, Joan Fontaine in Rebecca, Katharine Hepburn in The Philadelphia Story, Ginger Rogers in Kitty Foyle, and Martha Scott in Our Town.
That year, Hollywood consensus held that Hepburn gave the year’s strongest performance, arguably the best of her career, for which she had been cited by the New York Film Critics Circle. The Academy winner, however, was Ginger Rogers, earning an Oscar for her first and only nomination, for a decent performance in a mediocre film, “Kitty Foyle.”
Was Ginger Rogers compensated for being so popular as Fred Astaire’s partner in the great RKO musicals of the 1930s. Did the industry feel this was her only chance to get the coveted statuette? How crucial was the inlfuence of her mother?
Was Hepburn placed aside for having already won the Best Actress Oscar very early in her career, for “Morning Glory” (1932-33).