If they put anything rewarding for Ranked beyond what they have now, people would complain the rewards they want require effort than passively gaining EXP.

as i said long ago in a post about this whole thing: By taking away a need to do Ranked they eliminated true "fomo" of PVP but also doomed it to being not desirable to be ran at a competitive level. That and they also eliminated Win trading by removing the ability to make a team of people you can properly coordinate with on CDs and abilities.

Face it: PVP since it's inception in 14 has and always will be an afterthought compared to RPers and PVE players.