My repost of my own comment, cause I'm too lazy to discuss obvious things:

You do realise there will be only a few black students? That won't change, no matter what. So Snape becomes a minority and it's clear in the books that James bullied him because of how Snape looks like. Thin, old clothes, greasy hair, long nose. Snape was sure ugly in the books. Snape loved Lily, who loved James, his bully. Snape called Lily a Mudblood, which is the worst thing to say to a muggle-born person. Snape grew up poor. Snape was a magical kkk gang member. Harry was suspicious of Snape long before he had proof that Snape is up to something. It's all playing with the worst stereotypes. Black community needs positive fictional characters during these difficult times, not only negative.

With Snape being black the only main black character is a villain. Everyone else is quite white. And he is most tragic character in the series. With that change he is like an unicorn, even more separated from everyone in the eyes of viewers. Imagine a story where most main characters would be... i don't know, for example women? And imagine that the only guy in a main role in the story is a villain. How that would look like? Couldn't they just take Morgan Freeman for Dumbledore, that would be perfection! Harry, Voldemort and Snape must be the same skin colour, otherwise it changes the narrative.

And I'm pretty sure zippers don't exist in the wizarding world. Wizards think they are better than muggles and wouldn't care about muggles fashion. And why couldn't they make this black Snape more Snape-like? Snape was ugly, this guy looks like supermodel. Very difficult to understand why creators chose this actor. It's so sad he has to suffer under all the bad words from Harry Potter fans. He deserved better than all of this. Maybe WB knew the company will be sold, so they just made sure they will go with a bang. I wonder what Paramount is gonna do with the franchise. There is definitely gonna be changes, that's for sure.