You only further illustrate the large issue that exists between melee and blm/smn in slaughter. You are essentially saying that melee requires voice coordination to beat ranged casters. And lets be realistic, you can't expect random players (most who don't even listen to simple things) to be able to run a coordinated melee train in slaughter. Furthermore, why doesn't range have to have the same requirements? Why aren't they required to coordinate?

That's right. All they have to do is sit back in a zerg full of players, pick a target and aoe the target and everyone around that target. No coordination required.