He's used to deal with extremely powerful flying threats like the angel legends and Adramelech (his ability doesn't care about their flying), or some other very powerful singular beast. He may not have the optimal life for his cost, but his massive 4 armor stops most threats cold, especially considering that very few big bads actually have piercing (Selesius has piercing +1 on her quick attack, I'll have to check the others). And if you use his taunt ability correctly, he can swing for ten dice when you need him to.
Again, I don't think the Warlord should just be throwing out threats randomly. Everything he has is meant to counter what your opponent does; the key is knowing which threats are appropriate when.