Zwarte Piet is an incredibly beloved character in the Netherlands and Belgium, he together with Sinterklaas has brought countless people joy when they were a child, including myself. It is therefore not surprising to still see people so eager to maintain the character as he is, both to maintain their childhood memories and because they wish for the children of today to have such fond memories of the celebration as well. There are of course also the general feeling that people 'outside' are trying to change something of theirs and the often mistaken belief that those 'outside' criticisms come with the implication that anyone enjoying the holiday in its current form is himself a racist or at least has conscious negative racial associations with the character.
All that said, there is nothing wrong with changing the character. Clearly there are those that are offended by the character, after all, without that we wouldn't have the video in the OP to start with, nor would it be a subject of discussion every year within the Netherlands itself. Now, you might think that the amount of people in the Netherlands who object to the character is relatively slim, and it might be, we have no way of knowing one way or the other. Regardless, does that make it right to ignore their concerns? Especially when you look at the other side of things.
None of the reasons children enjoy Zwarte Pieten so much these days; his kind character, his giving out presents and candy, his antics or any number of other things require the character to look as he does right now. Why couldn't he look different? Why couldn't the festival change with the times again? If it can't, why not now? Sinterklaas has changed at many points in history, in subtle or more overt ways. People arguing tradition should probably argue that the festival be celebrated in its original form, in which case we wouldn't be dealing with a blackface character at all..
