It's racist if there's negativity around it, as there was 40-50 years ago when they were mostly the dumb helpers (as in, acting like fools, speaking in completely incoherent ways), nowadays they are 100% associated with positivity, joy, happiness and everything since a couple of decades ago the decision was made that 'hey, getting these black people and making them look and speak and act dumb on purpose might be a tad wrong' (and rightfully so of course).
Anyway, any discussion about it is entirely impossible in the Netherlands, even though it comes back stronger every year, because the people who are strongly for keeping this tradition call you a traitor if you don't agree with them (which obviously is plain stupid) and the people who are strongly against keeping this tradition call you a racist if you don't agree with them (which obviously is just as plain stupid). Even better, if you're somewhat in the middle and you don't care so much (like the vast majority, including people from every colour in the Netherlands) you're called a traitor AND a racist because you don't entirely agree with both extreme sides
It's also fun when outsiders join in and go "you're all a bunch of racists and this needs to stop!". How very open-minded and non-generalizing.