Why Was Piety's Mercy Removed?

In the last Druid update for version 0.4.0, why was the support gem "Piety's Mercy" replaced with a completely unrelated gem?
Piety's Mercy was renamed to Dominus' Grasp.
Dominus' Grasp now grants Supported Skills Chain 100% more times instead.
Piety's Mercy prevented skills from killing monsters, which left them at low health so that other skill could finish them off. Why remove such a unique geminstead of creating a new gem? This is truly perplexing.