Arguments about race are certainly complex, but I don't think her initial letter was. She was responding to this article
https://www.theguardian.com/comment...ck-and-white-issue-it-is-far-more-complicated, and her reply, which very clearly stated she didn't think white people faced racism, and then added the comment about people with red hair also facing prejudice, was condemned across the board. Given the context of the article, about abuse/assaults faced by various ethnic groups, and the scrutiny Labour was under, it made pretty grim reading.
Her apology was made very quickly, and, despite the curious comments about it being a draft, was very clear, and appeared genuine. Certainly not the non-apology that many politicians make.
As I said, I completely agree that what she said yesterday was much more reasonable, and she could have made that argument many times without anyone batting an eyelid. In the context of it being a response to that article, it was always a very loaded response, and it appeared at the time that she regretted what she said. What disappointed me, is that by suggesting she had no regrets about the incident, setting up the straw man, and then claiming her critics were silly, she's clearly rowing back on the apology.