So Why is Threat Invisible?

That works great until you start getting yelled at for losing threat on an enemy and it two-shots the healer. (If they can hit that hard; I don't have a 50 yet.)

Why do we have an invisible game mechanic? It's like not being able to see health or resource bars. What possible reason could there be for this?

Some bad answers I want to head off at the pass: "I can kinda sense where my threat is based on how hard I'm hitting things." Unless you're an robot, no you can't. You just can't. And even the robot would need to know all the threat values anyway, and we just don't have this information. You might have a vague notion of your threat, but this is the whole problem I'm on about. Why not just show us like heath or resources?

"See?! This is why they need to give us mods!" No, they just need to show us the values in game like every other value; health, resources, resolve, cooldowns... again, why is this one value singled out for invisibility?

"See?! This is why people need to actually LEARN how to play their character instead of relying on something to tell them when to back off on the threat."

The most correct answer would be that "we don't know"; only Bioware does.

So instead, we should really look at it from the viewpoint of "what harm would it bring if threat meters were added"? Well, first is the obvious reason: developer cost. Obviously at the moment, developers are pretty stretched thin, fixing bugs, adding content, etc., so adding a new feature at high cost for minimal gain probably ranks pretty low on their lists. It's the same reason why addons/mods/macro support hasn't been added in yet, even though Bioware has stated clearly that they want this in some fashion sooner or later.

The second is something someone else mentioned: immersion. Now, personally, as an ex-hardcore WoW raider, I can never see raiding as anything more than spreadsheets, rotations, and so on, but there's still a large (read: ginormous) part of the MMO player base who might as well be playing with the UI turned off (and enjoy playing in this naive state). Adding more bars and more flashing UI things can hinder their enjoyment of the game, and let's face it: casuals are the moneymakers for MMO companies.

Difficulty: Threat meters would technically decrease difficulty, but would ultimately increase difficulty. The reason for this is because with a more technically empowered and enlightened player base, the raids must become harder to compensate. We've seen in WoW how the raids have evolved as an arms race between dungeon difficulty and addons. By adding in something even as simple as a threat meter, the dungeon difficulty would have to rise and possibly alienate casuals who were less able to use these tools.

Player communities: It was mentioned that threat meters might make them mandatory (which it might, but only due to the aforementioned reason stated before), and that hardcore players would belittle casuals for not using them. Aside from the fact that casuals will probably be doing less dps (lacking the theorycrafting knowledge to do so) so that their threat wouldn't even matter, I think this is a false statement regardless. Hardcore players are going to hate, threat meters or no.

Look guys, no one's worried, okay? Can you all stop waving your tanking e-peens around?

The question is "What reason is there to have it invisible?"

The question is not "Who can boast the most about not needing it?"