So....Coolness

[Krazysigmarite]

In 5th edition Warhammer, heroes were the central point of most warhammer battles and were easily able to take on entire regiments alone.

We are now in 7th edition, which is focused on combined forces - Sure, a dragon is powerful, but is it worth the potential 4-5 core units you could take instead of it? Heroes are also much easier to kill, and sending one against a regiment alone is suicide, unless it's one of those super-expensive faux-pas-to-take-in-a-normal-battle "Unique Heroes" that the army books feature - Archaon, Zacharias the Everliving, etc...