Why has the wartime existence of "comfort women" gained such notoriety in recent years? I'd suggest three causes: Japan's retroactive bad conscience; South Korean politics, internal and external; and the unwarranted U.S. propensity to be a moral scold.
Upon Japan's defeat in 1945, the U.S. Occupation told Japan to abolish "legalized" prostitution. Japan did, in January 1946. Why the U.S. didn't like the legalized aspect of prostitution is anyone's guess. Occupation personnel continued to make full use of Japanese prostitutes, including those in the Relaxation and Amusement Association (RAA) brothels specifically set up for them.
The official U.S. moral rectitude led to Japan's enactment of the Prostitution Prevention Law of 1958, but that didn't prevent the business of baishun, "selling spring," in any way.