Blackguards, Anti-paladins, etc. 'evil paladins' have had a place a long time in D&D and the Forgotten Realms. Heck, you could even fight some gith anti-paladins in BG II. That really doesn't bother me. However, as I see it, Paladins are a very RP-heavy class, and like with the Druid IMO, BG III just doesn't quite deliver there. For one, removing the datamined paladin deities in favor of ill-defined oaths is a pretty major letdown. It's removing so much of what you define your character with by just boiling down 'paladin' to 'this guy just swore an oath with so much conviction that it manifests as divine power'
And then you can just pay some cash and get off consequence-free. Revolving door paladin powers-just pay a small fee afterward and you can murder as many tiefling children as you want! Just pay off your local hellknight and he'll flip the switch to your paladin juice back on!
And then the oathbreaker class itself. Which goes out of its way to explain that it's even less of a commitment than a normal paladin oath, that you can be good or evil or whatever and it doesn't matter.
BG III desperately needs better player-facing information when you are going to break an oath. It needs the cut paladin religions back in. It needs 'evil' paladin oaths and not just 'noncommittal edgy paladin' that is the Oathbreaker, and it needs some proper questlines and lasting consequences around paladin's falling and redemption. The npc appearing immediately and giving you the option to reverse your power loss right then and there should go, redemption should be a quest, not a monetary transaction, ditto for the oathbreaker class. That should be something you earn.