Plans change, things happen, decisions 6,8,12 months down the line are vastly different from now. I personally have learned a lot about ideology vs reality over the last three years and this is a part of it. It's just the way things work. Should that promise have been said? Nope. Can we do anything about it now? Not at all.
You are right in that it's not correct for us to make promises for the future even if we can fill them. I doubt you will see us doing so much anymore about anything. In this way we will become like any other gaming company and not promise or even say anything until it's already done. Sucks.
That aside, my PERSONAL opinion as follows: It's not direct "power" since a hero is so vastly different in different people's hands. I could have a random baddie friend buy the hero and suck with him and he wouldn't see it as buying power at all. This is completely reliant on us putting out balanced heroes, which we are putting a lot of effort into lately.