And Bane actually made the armor and wore it before becoming convinced that it wasn't worth it and trying to get rid of it. That Nadd looked into it and considered it doesn't mean he had to have failed to do it.
Bane thought the armour was preventing him from making a holocron, but he was wrong. He then wanted to keep the orbalisks. I've not read the whole book but I'm unaware that it's said anywhere that Bane wanted them removed. It's said he "lost" them at the end, last time I looked.
__________________ “The galaxy must experience the pain of death and the rapture of rebirth as I have. I will bring chaos. It is time for war.”
Bane decides to re-evaluate after discovering that, but he doesn't dismiss the idea out of hand. There are clear downsides of them, like how he almost killed Zannah in a blind rage that one time. But really, Nadd could have just died before finishing his research. There could be any number of reasons why Nadd never went ahead with the armor. It's ridiculous to suggest Bane is better based purely on this.
__________________ "I judged the Poles by their enemies. And I found it was an almost unfailing truth that their enemies were the enemies of magnanimity and manhood. If a man loved slavery, if he loved usury, if he loved terrorism and all the trampled mire of materialistic politics, I have always found that he added to these affections the passion of a hatred of Poland. She could be judged in the light of that hatred; and the judgment has proved to be right."