Because that moment is symptomatic of the Forsaken - they are cowards who are only out of their own survival. No Forsaken is capable of pulling even a moment like Macbeth, where the villain realizes he's beaten and trapped but decides to go down fighting like a man. "Come wind, blow wrack/At least we'll die with armor on our back." and "Before my body I throw my warlike shield and cry 'Lay on Macduff'/ And damned be him that first cries "Hold, enough!"
In the same circumstance, the Forsaken would have been yanking down Macduff's pants so as to more firmly apply their lips, in the hope of preserving their own lives. That is what the Forsaken are - contemptible cravens so willing to do anything to survive they'd even submit to the Dark One's will. And they will never be as badass as Dark Rand, because none of them have what he did - a cause.

And justified. As other famous works have noted, there is nothing for terrible than a man who is acting for justice. Aside from the morally questionable act of channeling the True Power, which is highly specific to WoT, none of Dark Rand's actions actually count as evil. All the death and destruction he wrought, he did in the name of good and righteousness and justice. Granted, for most of tGS, there were far more moral options he could have chosen, but by real world moral standards, his behavior with his girlfriends throughout the series would constitute a graver sin than anything he seriously threatened or carried out in tGS.

Given that he is the most dangerous villain of the series short of the Dark One, how much longer could the world have lasted with him? As the prophecies say, "Pray that the heart of stone remembers tears, and the soul of fire, love." How long could the world have lasted with Dark Rand running around and the Dark One so close to escape?

Part of what made ToM suck was the array of mistakes in tGS which bore fruit in ToM, such as, for instance, Rand's epiphany which undermined most of the tension and danger presented in ToM. With him making spring and fruit and flowers and all that, how seriously can you take the dangers of rotten food and heavy cloud cover in the rest of the books? How big a threat are the omnipresent Darkfriends or Shadowspawn leaping out of thin air when we see Rand obliterating their armies and identifying Darkfriends at a glance? And what stakes does everything else have when Rand gives orders in the second or third chapter that are plainly a staging plan for Tarmon Gaidon? If he can come to Maradon's aid as he did, than Lan's fight loses a lot of drama and if he does die, it will seem like a cheap waste. What is more, while at one time Aviendha's experience in Rhuidean might have seemed plausible, can anyone really believe the transfigured Rand will make the errors that lead to the Aiel upsetting his new world order?

Acting in a blind rage seldom accounts for things like "secure them safely to kill at leisure." The way she behaved was entirely plausible - she lashed out to cause them pain, and then Rand stopped her, and suddenly she had her hands full with the most dangerous and powerful channeler in the world, and who was the person at whom she was most pissed, anyway.
Did you miss the very next book, where the quarterstaff is presented as the superior weapon?
That the only way Rand won was a suicide attack, which not only failed to kill Ba'alzamon, as he was right back in the next book, but inflicted upon Rand a wound that still pains him whenever B-Sand remembers it?

And how do you know what that entailed? He may still have been bound in some ways to Shayol Ghul, since he never really appeared in what could incontestably called "the flesh" and that fight might very well have taken place in some intersection of Tel'Aran'Rhiod and the real world, especially given the presence of the Heroes of the Horn. It may be that his bindings prevented him from drawing on his full power and thus forced him into a dream fight. Also, we see in ToM that channeling is less effective in such combats (and had hints of this in tFoH). In such a situation, attempting to channel at Rand might have been as ineffective as Nynaeve's attempts to burn Rahvin.

Meh. Boom, splat. Done. How often do we see Tuon with damane in constant attendance? Only when they are doing something Power-related, or she is on a ship with most of her household. Damane are scum and to socialize with them about undoubtedly makes one sei'moisev. Also, a treacherous sul'dam can wreak a lot more havoc than a disgruntled soldier whipping out a hidden knife and lunging for the ruler, so basic security would be to have them kept away. The idea of a mareth'damane infiltrating the Imperial Family and whacking them all would be fairly absurd to the Seanchan, and they don't know most of the techniques available to the Seanchan. As far as they would know, a channeler would have to blast her way in to do any harm, and the damane stationed in their kennels or patrolling the perimeter would be alerted to respond. For a channeler to be able to infiltrate all the mundane security and strike without detection would be inconceivable. And that is probably how she did it. You imply a wish to see her exercising a phenomenal burst of Power to overwhelm a mass of elite damane, but in all likelihood, she simply breezed in, slaughtered some defenseless nobles, and Traveled out again. Remember all the damane who served as personal security for High Lord Turak, the Empress-appointed leader of the Forerunners, and the representative of the Seanchan government on the main continent? You don't? Because there were not any, which is how a farmboy with less than a year's training in swordsmanship was able to wander in with four friends and kill him man on man.

Because he's a petty little bitch like the rest of them, and no match for a good guy pushed over the line, like Dark Rand.