I understand where you're coming from, but you're forgetting, Joshua essentially was the Hanged Man during his decades as the Malpais Legate. When he was set on fire and thrown into the Grand Canyon not only was he, a man who as the Malpais Legate, went from humble Mormom mission to this arrogant, proud, and ruthless war leader, shamed and humiliated, he was also stripped of his title and earthly posessions. I think when he was lying in that canyon it was then something deep inside of him reawoke, but in a sort of Janus way, one side of his soul wanted to seek forgiveness from his family and get close to God again, but another part over time when New Canaan fell, saught to use God to justify his brutality, to justify his over the top coldness as God's wrath, this is even pointed out if you pass the end DLC speech check. I disagree with you thinking of him as a cliche, because his character is more than just 'bad guy slowly turning good', his character is more along the lines of a man who fell from the mighties power, and went back to his roots, but inside he's struggling to control his depraved nature he'd known for so long as Edward's right hand.

I still found him boring, part of the reason is because of his redesign and part is because I don't like real world religion.
His character didn't need change, I see his change as much of a positive as I see Harold's change.