In my opinion, apology is worthy only when the target knows what apology is. A person who knows it shall express apology when he/she does something wrong.
Have you ever seen that Korea expressed any apology? I have never seen before!
According to by SCAP, also known as GHQ, those Korean people who lived in Japan killed more than 4000 Japanese people after the World War II. They reviled Japanese people like "Japan was defeated. Korea won the war!" Right after the war, Japanese police were disarmed and there were only women and children. Thus, Korean male riots easily killed the weak people. I'm really angried about this affair. I have never heard Koreans express any apology for it before.
Why so many Korean people were in Japan? Because Japan and Korea were a same nation due to Japan's Annexation of Korea. Korean soldiers faught within Japanese military, killed lots of enemies, had sex with comfort women. While Japan was defeted on World War II, Korea also had a part of responsibility for the war. Have you ever heard that Koreans expressed apology for World War II?
After the World War II, Korea passionately attempted to extend their activity sphere. When Japan was disarmed, Korea declared Syngman Rhee Line unilaterally. Due to this lawless affair, 3929 Japanese people were arrested, of whom 44 were killed, and 328 Japanese ships were seized! This was not a war. I have never heard Koreans expressed any apology for this affair! What is even worse, they still claim sovereignty over Takeshima. Syngman Rhee Line is of course void in the current international law!
When we talk about Korea's responsibility for the war, "Lai Đại Hàn" is a must topic. See what Korean soldiers did during the Vietnam War! Have you ever seen Korea expressed apology to Vietnam? I have never seen before.
Conclusion: Koreans do not know what apology is at all. Before blaming Japan for comfort women (they were sex workers, not sex slaves), Korea government should express apology against what they did in the past. It's not worthy to express apology against those who do not know what apology is.