All four of those articles go out of their way not to discuss any particular races at all, in the context of dating. Of the four, I think the one on everydayfeminism.com probably gets it the best: it's okay to have preferences, same as you might for hair or eye color or height or whatever else, but depending on the strictness of your adherence to your "rule" - yes it's racist.

So the articles you've linked are fine, IMO.

However I do get the sense and agree with you, that for a great many people it's only racist if you're white, and that for other ethnicities racially-exclusionary dating is fine. Mainly I think that's because most people haven't given it much thought.