Because racism is a problem and problems tend to want solutions. The implied solution is '...therefore to diversify you must now ship interracial pairings, which will involve a lot of play-acting on your part if you're not attracted to them and producing content related to them if you would normally do that for a white ship'.

It's really just the same ship war bullshit there's always been, but with just enough connection to real world issues that ship failure becomes MORAL failure.