Achievement Pet Peeve

If I hear my guild say one more time "We need this class to do this" I'm going to snap my keyboard in two. It would require Hulk strength, but one more mention that we *need* a priest or we *need* a death knight or we *need* ranged or we *need* melee, I'll turn green and my muscles will rip my tabard apart.

So far everything we've tried with the makeup we end up with has eventually worked. But usually its not without someone griping over vent that we need this type of tank or this type of dps or this type of healer.

Most guilds don't have the luxury of picking and choosing what classes to take to what encounter. And even more importantly, is it fair to all of your Class X when you decide Class X just won't fit the bill for your raid composition?

I get the "bring the player not the class" philosophy, because am I supposed to miss out on getting certain achievements simply because I'm not a Y or a Z?