If the character you play made a decision you disagree with....well...it wasn't your character.
You remember the rock-paper-scissor mini game in DOS, through which you and your other custom character try to settle a difference in opinion? If you want to go with option A then LOSE the rock-paper-scissor game, your characters would go with option B, and you'd feel like tearing your hair out. This is literally "the character you play made a decision you disagree with".
I'd also like to point out that "play the game the way you want" is not the same thing as "everything works out the way you want". It is understandable if we want to avoid unpleasant consequences that result from NPC autonomy. However, there are times when that makes sense and adds life to the game. For example, the idea that two party members suddenly becoming unselectable and trying to kill each other off. I understand that this could cause inconveniences, and many players can't see the amusing side of it and to them this idea is just bad. Personally, I find this amusing and wouldn't mind either reloading the game or just moving on. I also understand that this is actually a consequence of my choice, which is "forcing people who hate each other to travel together".
I guess many players can't stand NPC autonomy when it's something unpleasant, especially when the situation stems from inconspicuous, seemingly "innocent" choices (meaning they can't anticipate that a certain decision they've made is going to lead to something unpleasant). Things like party members suddenly leaving you to do their own things, becoming unselectable, trying to kill other party members, hating your actions to the point that they immediately turn hostile, disappearing from the game for good because you don't help them in time, etc. The old BG games weren't afraid of creating such situations and putting you in a rough spot, and I respect them for it.
In BG3 we see NPCs interacting with surroundings (blacksmith hammering, workers using their tools, people near tables and chests interacting with them) as a part of their routine, there are more animations and voice over for idle NPC routine in BG3 act one than whole BG2, even the text for idle NPCs is very limited, used mostly for town criers and quest NPCs trying to get your attention, usually you have to actually talk to them to see their dialogues with other NPCs.
So we're just talking about two different kinds of "being alive" here. You're talking about the animations, voice-overs, and idle interaction between NPCs and world objects. While these are nice and they make the game feel exciting and animated, they are just cosmetic, on-the-surface things that you can see, and rarely have real consequences. Let's take the blacksmith hammering for example. So what if he's interacting with his anvil? Does that mean anything? If not, then he's no different from an NPC standing still doing nothing - the only thing the blacksmith has that a static NPC doesn't is the
animation. Now, however, if you can take his anvil away, and he actually realizes that his anvil is gone, and reacts to that in some manner (maybe go out and buy a new anvil, post a notice about his anvil being stolen, etc.), then that would make him more "alive".
While "NPCs looking lively" does add to the feeling that the world is alive, the kind of "being alive" that the other guys and I are talking about is beyond that. It has to do with the personality of NPCs, the things that they say, the stories that they tell, their history, their
reaction to world events, and the way world events happen. These are the things you don't immediately perceive like all the cool animations. They involve more
writing. It takes good writing, and it takes reading and playing time to see and appreciate. Voice-overs certainly help add personality to a character, but it takes more than that for the character to feel alive.
