How is the game supposed to know that you've changed your mind? How is it supposed to handle you changing your mind?
Should there always be a "wait, I changed my mind about everything I did" option every time you talk to your partner? What if you didn't change your mind about everything, and wanted to keep some choices the same? You seem to be asking for a way to go into your Personality Profile screen and change any of the values to anything you like at will. That's not a good idea.
Think of the personality profile as the impression you're giving to your partner. Impressions are hard to go back and change later. Every time you increase your faith, that's how your partner sees you. It would be hard to believe someone who says "that old me is terrible now, I am changing."
"Action speak louder than words". You can't just say you'd take them all back, you have to show you mean it. If you regret your earlier alignment choices - MAKE DIFFERENT ONES IN THE FUTURE. With a person, the slate cannot be wiped clean, and all your actions forgotten. Why should the game artificially try to make its characters seem more artificial by letting you wipe away the impression you've given?
I think you've seen the parts where Larian is trying to emulate the feel of a tabletop pen-and-paper RPG, but this is a videogame, it's much more structured. It's a bunch of algorithms stuck together to try and simulate human behaviour. It will have trouble handling complex things like "I'm going to roleplay a Paladin who starts out faithful, then acts like a jerk, so GM Bob, you'd better have all the NPC's react to me exactly like that."
