I've always preferred restoration druids to perform a Heal-Over-Time role. Burning Crusade encounters were unbearable without a tank have Lifebloom and Rejuvenation ticks constantly on him. The fact that blizzard now wants HT to become part of our arsenal of spells kind of strays me away from my role. I provide the highest constant HPS on a tank without having to constantly looking or casting on him.
Glyphed regrowth which strikes critically (when talented) at least 50% of the time, combined with nature's grace becomes a pretty powerful and efficient Flash Heal.
PS As to the Replenish use, Blizzard (along with the glyph) wants us to take this talent (and the idol which reduces mana cost) to raid heal, where gaining mana, energy, rage and runic power alot better. Granting a rogue more energy, a priest more mana, or a deathknight more R Power might be beneficial in several encounters.
(Thinking back to the days of the 2PC T3:
http://www.wowhead.com/?itemset=521)