Zwarte Piet ["Black Pete"] is a syncretism, and originates thousands of years ago, all the way down to the Roman era. Shamanism is a great example here. They also paint themselves black (face and whole body), which has a meaning. Should we consider them racist too? And we took more symbolisms from that era, too. And if you combine both the fest of Sinterklaas with Wodan / the Yule fest (yes, often known als Odin, the All Father in "Thor"! He's an Germanic God), you might find quite a few similarities...
The same thing, a syncretism, happened with the Greek Gods and Christianity. It happens all the time if you look at our history. Religions and such sometimes get mixed together in order to prevent a society from collapsing, and to improve from it, to get stronger out of it (well, the Roman Empire still collapsed, but you know.. minor detail). Hinduism itself is a syncretism!
Going back to the issue at hand, it's ridiculous. Sure, the Dutch are nowhere near tolerant as some of us like (or claim) to be, but making this tradition, which -mind you- a teacher wrote for children back in 1850, racist is absurd. At least, it's not treated that way. Black Pete is the good guy in the story. You better watch out for the pervy old dude! Let alone the helplessness of Sinterklaas. He cannot function without his Pete's. He needs them desperately and each has their own task. Aside from that, they're often the people with a warm, kindhearted spirit. Yes.. we're definitely promoting racism here. There's nothing hateful going on there.