He's not giving him red hair, he's bringing it back. Four Boy Wonders with black hair and nothing but height and costumes to differentiate them from each other is a bit weird and dull. Adding a bit of the pre-Crisis Jason to make one of the Robin's immediately standout from the herd isn't a bad idea.
Jason was killed off because nobody liked him. If that has changed it's because of the way he's been written now.