It seems like Aura has more than just a defensive role, Lie's pink Aura (the manliest of Auras) was flashing when he hit the Snake Grim's fang so it can also project force as well as deflect/mitigate it. On a side note Aura probably explains Yang's Super-Saiyan mode, so it's possible that Aura is influenced by emotions. red-head=Pyrrha Nikos.
I think it's because the allure of having these new toys to play with diverts from the main cast for now, it will probably even out given time.