I can understand that. But, at the same time, to the best of our knowledge, Tyler Christopher did not have Greek-Russian ancestry. He was Scottish, English and German. But his darker features helped him, and Adam Huss has those features in a much more subtle way. Again, we've not yet see Huss beyond pinch-hitting for Marcus Coloma (who shouldn't have been cast), and he hasn't really played Cassadine much. I could see Huss vs. Constance Towers' Helena, but I can see why others wouldn't.
In truth, to recast Nikolas again would be futile from my opinion, especially since it's clear they're dedicated to Huss' work in the role and he's willing to work when called.