Yes, it is racist and I doubt that most people would be able to argue that it's not. However, we aren't talking about racism's dictionary definition.
I think everyone in the thread basically wants the same thing, which is a less racist world. We all want to be judged as individuals, rather than as members of some group identified by its skin color. We disagree only on how we are going to get there. Some of us think that actively promoting diversity will eventually achieve a lower level of racial consciousness. Others think that this is akin to trying to fight racism with racism, and all you will manage is to put society in a perpetual state of suspicion and mutual hostility.
Why do you use "white," "black," and then "Chinese"? There are multiple versions of white and black, and not all east Asians are Chinese. I've been trying to avoid talking about myself demographically, but as someone who is east Asian and NOT Chinese, this bothers me whenever I see it.
There is a tendency in the US to niavely imagine that ethnic/racial groups can be lumped into a few broad categories based largely on skin color and that these are perfectly descriptive. In this conversation we've all implicitly talked as 'white' was a single racial and ethnic classification, 'black' was another, and 'Asian' was another. These is even a tendency to assume that by racism, what is meant is whites hating non-whites (and very rarely perhaps the reverse).
In fact, the world is not nearly so neat. Outside of North America, 'whites' do not necessarily think of themselves as belonging to the same ethnic group as every other white person, 'blacks' do not think of themselves as belonging to the same ethnic goup as every other dark skinned person, and Asians certainly don't think of themselves as belonging to the same ethnic group as every other Asian person. In just the past 30 years, we've seen genocidal acts of racism by whites against whites, blacks against blacks, and asians against asians. The worst explosion of verbal racial hatred I ever witnessed wasn't with the redneck kid whose family was in the KKK, but from a Chinese and Korean friend who started talking frankly about what they thought of the Japanese.
I think we vastly overemphasis the role of skin color in 'diversity'. I think if we aim for real diversity, we will bring skin color along almost as an after thought. I think if we will diversity by just letting the hobby diversify, so that the players, referees, designers, writers and artists are diverse. I think we are getting there, but that we have a long ways to go and there are no shortcuts. I think if you make a symbolic act of putting a visual representation of someone with an unexpected skin color from the context before you do the hard part of creating the context, that you aren't really accomplishing much of anything at all.
To be honest, I'm really torn over how I feel about this. I'm not really objecting to the result of illustrations of characters with diverse hues, but the particular process for how we get there which some seem to advocate as, to overly simplify, "Don't add real diversity, but paint some colored folk in to make it look good." But I also recognize the reality that achieving a diverse hobby is hard, as unfortunately the evidence is that there are a large number of minorities out there that won't feel included until someone takes the first step of giving them something that they can racially identify with. It would be nice to imagine having been yourself been defined by someone who defines themselves according to thier skin color, that it would make you less likely to yourself repeat the mistake of defining yourself by your color. But it doesn't seem to work that way.
