I think it would be great during 5mans to be able to charge into a group of mobs even without any rage and maybe even generate rage by doing so. Might kick my Enrage habit and make it a lot less punishing when we have no rage or enrage. (The slow run into a pack of mobs is slightly embarrassing)
Lets be honest, even if they removed the rage cost its not going to break anything - its cost is only 5 rage at the moment. All it would mean is if you are stranded between pulls with no rage or enrage you would be able to do something.
Now that Feral Charge is only available to Ferals as well, I can't see much logic to the 5 rage cost, or what it is meant to achieve.