Shadow of Mordor and Shadow of War actually explore orcish culture and morality, the latter game more than the former. Ultimately, they’ve spent all their lives in a Morgoth and/or Sauron cult. The ones that don’t buy into it are more chill, and some show signs that they could be decent or even heroic in different circumstances. Eltariel is able to make some progress deprogramming a couple, but siding with Talion, Celebrimbor, or even Eltariel mostly just has the orcs cast them as their new Dark Lord. It’s probably possible to get the bulk of the orc population into a better place, but it would take many generations of concerted effort at a massive scale. They’d have to replace their entire belief system and most of their way of life just to leave the cult. Additionally, even when not following a Dark Lord, the orcs culturally favor bloodshed to settle conflicts. This isn’t too big of a problem with other orcs since they can take shockingly large amounts of punishment without dying, but it’s a huge problem when interacting with anyone else. And even that’s probably solvable without wholesale destruction of orcish culture, but everything would take so damn long that it’s well beyond the scope of LOTR.