1. True, it was added late in WOTLK's life cycle.
2. So? Heirlooms are a good thing. If you want to level without them, don't use them. They're an option for people who want them.
3. Did you forget that BC had heroic dungeon badges as well as Sunwell Pinacle dungeon? This started in BC. The only major thing Wrath did was remove attunements. BC introduced catchup gear.