I grew up with blackface (zwarte piet), sung about him/her, even was one on occasion. Never thought anything about it. Until out of nowhere I get called a racist and people show up screaming "Racist!" at a, what was always, just a fun time for kids.
Sure, I, and many people in my country, had a reaction against it, very conservative in nature. But now, over a few years and seeing some reasonable people explain to me that zwarte piet hurts them and that the hair, the lips, the earrings, the slave-like behavior in songs is really quite racist. I, and many others changed their mind. It also helped when I talked to people that held the opinion that I am/was not a despicable person for taking part in this old tradition, there was no "original sin" that I should feel for the rest of my life.
And so a lot of people in my country changed their mind. Sinterklaas is a kids party/holiday and it should be inclusive. Kids couldn't care less about the color of zwarte piet of course. I and everybody I now know is glad we changed course, or rather are still changing course. Mostly smaller villages defiantly keep the old black face, but it will rot away, as it should, over time. It takes time to convince those people, or perhaps they are too stuck in their ways. My grandma lived through WW2 and still always said horribly racist things (i.e. a common saying was that if a river was dirty, "the Turkish people swim in there."). You really couldn't change her anymore. She also lived in constant fear that Islamic people will come to our country and, "since they all live together in small houses, they will come and live with us in our houses if we don't protect our country".
I also cringe at children's books like Pinkeltje (first part published 1939) that I have lying around from my own youth and read to my children until I hit parts that I really couldn't read anymore. Parts are pure racism, i.e. in Africa Pinkeltje is basically battling small black devils, really portayed as sub-human. It takes time for people to see it, to see it as people of other races experience these texts.
I'm 100% on your side now, and I reason with people that aren't and I try not to judge. Easy for me to do of course, when you are at the receiving end I can imagine screaming "Racist!" at a kids party feels, and perhaps is, the only way towards change.
Btw, I also cringe at our still very popular "Jip and Janneke", Jip is the boy, always dirty and mischievous. Janneke the girl: Always clean and vacuuming with her mother and doing the laundry. They also get candy for anything they do well. I tell my daughter she can be a knight, does not have to be the princess. But these things run deep in our culture, and we should get rid of them.
I know it does not really make sense, but I apologize to you and to people that felt hurt. I didn't see it. Thank you for your sustained effort to make me see it as it is and how you experienced it. The world our kids grow up in will be better because of it.