MLK Jr. is more than an important historical figure, he is a turning point in American history. The reason many on the right don't like him is because they credit him with "modern activism". But that's not fair. He bravely fought for civil rights.
The people (modern activists) who took up his mantle fought for the right to enslave and exterminate. There's a big difference. The first one prioritizes freedom, the second one prioritizes corruption, slavery and death.