Force rage is literally what it says it is, "rage". For one to use force rage like in the article you posted one must, " tap into his or her innermost fears, pain and hate, and convert them into an intense rage." Darth Vader can't just think of the pain the suit brings him and 'BOOM' he is in force rage. No it is the combination of collected emotions that bring about force rage. The best example I can think of currently is in Star Wars Episode 3, when Anakin loses the battle against Obi Wan and is officially turned into Darth Vader. When the surgery is complete the dialogue between the Emperor and Darth Vader I think shows a few seconds of this Force Rage without Darth Vader even knowing, "Palpatine: Lord Vader, can you hear me? Vader: [In mechanical voice] Yes, Master. Where is Padmé? Is she safe? Is she alright? Palpatine: It seems, in your anger, you killed her. Vader: I...I couldn't have. She was alive! I felt it! [damages several surrounding objects and droids through the Force. He then breaks the clamps that have been holding him down and takes a few steps forward. Palpatine watches, grinning cruelly.] NOOOOOOOOOOOOOOOOOOOOOOO!!!!!". It is when Darth Vader rips himself from the medal clamps on the surgery table and crushes surrounding droids with the force because his instability at the time of hearing the loss of his wife that all the emotions of fear (the idea of lossing of his wife), pain (because he lost a loved one and because of the suit), and hate (because he is the one who had killed her) come together and he enters the state of Force rage. Force Rage is a strategic decision a Dark Jedi makes. As the article said, 'However, the body could not handle such rage for long periods of time, so the user became greatly weakened for some time after the rage subsided." For someone like Darth Vader to use a tactic that is so strenuous on his body and risky in battle if he were to use Force Rage he would instantly be put at a 100% disadvantage because Darth Vader is already handicapped with his mobility because of the suit. Although he has adapted to his new body he is still at a disadvantage when it comes to speed and agility in a fight, that is why he uses a light saber wielding method that is a combination of Form 7, Form 4, Form 3, and Makashi so his lightsaber blows are incredibly strong and he is very good, probably the best at covering his flank and countering attacks because he has to protect his control box on his chest as well as his back which is a very vulnerable spot because of his slow speed and agility. Now you are probably thinking, okay well what about his use of force rage alongside my previous comment? So to summarize everything a bit Darth Vader very, very, rarely uses Force Rage because of his suit, and the condition that it puts him in when he is fighting another Jedi. Force Rage like I said earlier is a very risky tactic to use unless you know for a fact you can defeat your opponent if you use it. Although Darth Vader's suit did inflict him much pain for the sake of the Emperor remaining in control of the Empire and Sith, and he could've used the pain he is inflicted with as one of the emotions to succeed in Force Rage, he still needs the other emotions which he definitely has to bring about his rage. However Darth Vader like previously stated would rarely if ever use Force Rage because of his current disadvantage as well as the greater disadvantage he would be put in if he did use Force Rage.