You specifically suggested removing an ability I find useful. I never said it was super-strong, but I was specifically taking exception to you calling it useless fluff and trying to get it removed from the game.
And I yet I've Turned things just fine in base-level-19 quests, on Elite (so "level 21" by the way you're calling Madstone 16), on a first-life Cleric not particularly Turn-specced, or even on a Paladin, and neither of them Sun Elf, either. Even Orange-named. This rapid-downhill-after-level-8 does not match my actual play experience.
In my experience, Turn Undead works fine in all Heroics. I'm sorry you're having trouble with it.