Because black people, in general, don’t have a slavery fixation. The creators of the GoT series currently have carte blanche to do any show they wish, and this is what they come up with? This show could only really go one of two ways: it will depict slavery in all it’s horror (and who wants to see a TV series featuring that in 2019?) or it will minimize the depiction of what slavery actually was, while humanizing the perpetrators in the slave trade in the process (um…really?).
When the VAST MAJORITY of black people that are speaking up about this are against this idea 100%, and are absolutely not here for it, perhaps they can be taken at their word that this might not be the best idea? Are we not there yet as a society? Does society (and by “society” I mean “white people in America”) really still not give a damn how black Americans feel about things like this?