All roles are equally important and depending on the fight, one role can be a little more important than another. One of the most useful and more important mods in the game is recount/skada, not for the dps or healing meter, but for the damage taken and damage taken from "source". This can be a quick way of knowing why people are dying and will tell you right away if its the healers fault or not. If damage taken on the raid does become a true issue you have logs to dig through to correct the problem.