Bone Harvest

I am curious with the new Blood Knight set why none of the builds using the set seem to use Bone Harvest. I have not used it much as a skill before but it seems like it would be really powerful with the full Blood Knight bonuses. Has anyone tried it and what are your thoughts?

Bone Harvest is more of a caster skill, while the Blood Knight set is more of a fighter set (fighter means someone that uses his own hands to smash their enemies, for example Cadence user or FS user or eventually dual wield character that uses procs).

80-130k dmg. with Bone Harvest and 100% vitality damage
2.6sec. cooldown, double BH (Time Dilation)