PvP Raids have gotten really discouraging for me lately, mainly due to runes. I have no way of knowing if an opponent is my skill level or twinked beyond any hope. All my heroes are the maximum they could be for my level; max runes I can make and yet I will find people who have 3 times my hit points or damage yet my power is higher than theirs. In the past, I would just avoid these people by looking at ascended level or stars. Team Power is not properly measuring the danger of a hero. For example, if I put runes into Kira that triple his attack, his Power rating only increases by about 10%.
TLDR: Make runes accurately change the power of a hero so you can know if you should challenge someone.