Low throughput heals served a role of feeling like the auto attack for healers. Do healers frequently do nothing during combat?
Your efficient single-target heal (Healing Wave, Holy Light, etc.) should still be a mainstay. Unrelated: Big fan of Healer:ALitD (WatcherDev)
Having a heal you can always be casting without worrying about the mana cost seems important to prevent healers just watching.
Agreed, I see the value there. For some, a DPS filler can work fine (free Lightning Bolt for shaman, Atonement for Disc, etc.). (WatcherDev)