I'm not sure showrunners understood what made Lethal Weapon work. First - it's a story about friendship with crime in the background not the other way round. It won't work in a standard cop+magical sidekick solving crime of the week setup.
Second. It's not just a story about white cop/black cop, it's based around younger trigger happy suicidal nutter and an old school, cranky, "too old for this ****" pre-retirement desk jockey who constantly gets yanked along for a mad ride by crazy antics of the former. Clayne Crawford makes terrible Riggs but also Roger's character deserved at least someone like Wendell Pierce or Andre Braugher.