I'm really surprised to find that GW doesn't playtest new rules as much within the community. That's a given when crafting a game system. I think Warmachine is going to run into the same problem further down the line, since it becomes harder to balance once you start adding new factions (something they've mitigated somewhat by also updating each faction with a model or two when they release a new army).
I think true balance is not quite possible, since the meta with always get bent to favor certain builds. It happens MUCH quicker now because of copy-paste lists. I think it's not a bad thing to work towards though.