I may be off-base, but I think the timeline went something like: Sacred Soil was bad because it was mutually exclusive with Shadowflare, which was better for damage and had the slow. Then Heavensward added Indom and almost completely relegated Sacred Soil to the trashcan because a pitiful 10% damage reduction for a short bit was basically always eclipsed by a big fat AOE heal that restored more than SS prevented, so even after they started rolling Shadowflare away from Scholar it still sucked. It's still only really good after it gets that ridiculous regen effect on it. Before that trait, Indom is just better.