Tsundoku, I understand your pragmatic point. Don't put that slogan on a black child and no possible problem (probably).
I am not sure that the options are that they either do not use it or they deliberately chose to be racist, or they at least intended to be provocative.
For all we know they all might have tried it on, but for whatever reason the photo with that child just came out best. And it is not impossible for a company to either not think of, or misjudge the reaction that the public or section of the public might have.
All speculations aside, what happened, happened, and if someone says that they ought not have done it, they were wrong to do this, then they are asking people to modify their behaviour. The people involved should have made a different choice. Nothing wrong with that per se. I'd be quite happy to tell a company not to do something when what they want to do will both offend people and there is a reasonable basis for that offence.
I wouldn't personally tell a company not to, say, include a gay married couple in their ads even though this is likely to be objectionable to some members of the public. And that is because I do not personally think that their offence has a reasonable basis to it.
So I guess what I am truing to say is, and this is just my opinion, but if the offence some people might take is "reasonable" then you are probably wrong for putting out that ad or material. If it is not "reasonable" then you can still argue that it might be best not to do it for pragmatic reasons. But I don't think there is the same level of moral imperitave for not doing it.
Of course what is "reasonable"? Use of a word that was created as a pejorative? Yes IMO. But here, a black child wearing a generic 'coolest monkey' slogan? Since the only reason I can see for this offence is that it reminds some people of racism, not sure personally. Just my opinion though, as I say.