"Even if you never thought about it, being able to customize your character's powers with multiple colors to match their costume or their theme is something that nearly every player will want to do, whether at level 1 or level 50. And since you can have different settings per power, and per costume slot, we wanted to make sure you could make the best of this feature when it goes live."
Oops this quote would answer the OP's question better. Teach me to read the whole article...