I don't think its too much to ask to have a SPriest, Retadin or Survival Hunter in your raid (well, having a Survival Hunter is a bit much to ask right now :P). That's like running a melee-heavy group with no Feral Druid or Fury Warrior and yelling at Blizz that you don't have 5% increased chance to crit. Instead of having one spec of one class with a niche for mana return, its been extended to three.
And on the point of "bring the player, not the class", Blizzard has specifically said this isn't a sweeping generalization, you can't bring 25 warriors and expect to win. You get all your essentials in the raid (and every essential is spread across multiple classes), and then bring who you want after that. If you consider Replenishment to be essential (our raid having both a consistent SPriest and Retadin, I don't really know how we perform without it), then you bring someone with Replenishment. If you don't consider it essential, THEN bring the player, not the class.