Hey you. Yes you, the guy watching TV while pressing the buttons. Yes, we know you're not paying attention, you stood in (fire) and expected to be healed through it. Actually, you probably didn't expect to be healed through it. You didn't expect anything, you weren't paying attention. Oh, now you're bitching about fail-tanks and shitty healers, how nice.
Everyone's run into this person at some point. Hell, some of us may have been that person. As much as I like to be on top of things, even I've zoned at times in my umpteen millionth run through H. UK, didn't get to spawns fast enough in VH, and so forth. It happens. We all screw up sometimes, or zone out, and the biggest culprit is simply not paying attention. Don't do this to your fellow raiders. Be there for the fight.
You might be the best healer on your server, the top DPS in your group, or uber-tank extreme, but if you're not paying attention, you're not healing. If you're eating the floor you're not DPSing. If you zone out and miss that taunt your raid is gonna be zoning in again in a few moments. It's important to be there for the fight.
Paying attention can save your (virtual) life. That stuff on the floor? It's bad. Anything on the floor is bad. Even if it's not bad, stay out of it to be safe anyway. Don't make your healers cry. If they have to spam heals on you, guess who's not getting healed? That guy over there keeping all the big bads pissed, that's who. When it comes down to decision time, the healers know what to do, they'll heal whoever they think will get it done, and if they let you die...well, they had their reasons (double check before bitching; raid tank survival may have been critical, tank was taking a beating, the healer was dotted and saving themselves. Run the checklist before deciding they were just being a dick).
This goes for tanks too. Tanks pretty much have to be there and on their game. But sometimes tunnel vision kicks in. You're nailing your rotation. The boss's health is dropping like a rock. You're doing it, you're badass, you're that tank, oh yeah! But wait, why'd the healer oom? WTF, DPS are dying? What the hell guys, what's...oh. Oh no. You were tanking in the sludge. Standing in the DnD. Not watching your range and all the DPS around you got Chain-lightning'd. Oh noes, everyone died and you're next! You went from being OMGTank! to WTFTank! with incredible haste.
Situational awareness includes DPS, threat, healing, and so forth, but that is only a small part of the equation. You have to know where you're standing, what you're standing in. Everyone has a specific role in the raid, and while you should know what your fellow raider's role is, trust that they'll do it. If you're worrying about "That Idiot over There (tm)" you're probably not performing your own role, you're distracted. A proper raid is a well oiled machine, and everyone should know their role. Once the action starts and the proverbial brown stuff hits the metaphorical spinning thing you need to do your best to:
- Stay alive
- Keep a tank alive (see #1 if this is you)
- Save a healer's life
- Do your best output (threat, DPS, healing)
- Don't stand in bad stuff?
- Don't stand in bad stuff.
- Don't stand in bad stuff!
That pretty much sums it up. These things are important, and knowing your role, your position, and your current situation will greatly increase your chances of survival and a successful raid. It seems like common sense, but that stuff is sometimes more like Common Sense.