Well I personally don't think the kit is as easy to pick up as wolf, blaze, or creeper, skeletal horse is broken. It's combination of bone rush, bone kick and deadly bones makes it very difficult to approach and bone rush + attack + deadly bones can take away 10 hearts instantly. Bone kick can also lead to cheap kills even when you aren't on a ledge as the kb is crazy. On certain maps they can camp in spots and make them virtually impossible to approach. Along with dealing lots of damage the armor is strong and the cooldowns are relatively short for how effective they are. I've seen a significant increase in the amount of horse players to the point where there is one in around half of my games. The game was already unbalanced enough as it is and now it continues to get worse. The horse needs to either have deadly bones removed, or an increased cooldown on 1 or both of its abilities.