why do they still play on the radio when they hate him

They no longer hate on him after his death.
It's just like every valuable thing , 你 don't get to respect it when 你 have it and 你 do realize its importance once 你 don't have it anymore. But yeah , still some stupid people dislike him. Haters gonna hate 你 know. No matter what.
Even when he was alive , still his songs were being played on Radio I believe like "Heal The World" , "Billie Jean" etc. No matter how 你 look at him , turn a blind eye 或者 not. 你 still can't deny his excellent music.
His 音乐 had great messages in it.
:D

Some people hate him and enjoy his music. One of my classmates hate him and talk bad about him but during our school's talent 显示 michael jackson's bad was played and he even sang and danced to it although he hates him.

Like i 说 michael is de king of pop but thy hate him