I (and some others) enjoyed the "Dark Approach" it made the MC feel different than the usual MCs we usually get. You didn't have to shoot at the teacher or etc, you chose to do those things. That's why there are choices, to avoid choosing stuff you don't like. Don't like being Dark? don't do dark shit.
I am pretty sure Chapter 4 was done without the "Dark Route" in mind. That's why it is the way it is. He made sure it wouldn't make sense now and is all about going the pansy way.
Of course you can "choose", thats not the point.
If you implement those dark things, the whole game is a different one and you expect more of those really dark things to happen. Even if you dont choose to act that way. And there were already scenes with the MC that were kinda dark without any choice given to the player... like some dialogues or monologues (right before the possible shoot he is talking to Vic that he better put her out of her misery for example which leads to pulling out the gun in the first place, and thats only one example there were many more)
But as i played chapter 4... the whole dark approach early on didnt felt right anymore, the whole game got a little "lighter" in the mood, and the MC himself too. And that didnt worked out anymore cause nobody changes that much in a few weeks. So yeah, the rework makes totally sense just for consistency.
Would i have a problem if the whole game have been darker the whole time? Not really, the first chapter got my attention already with the initial release. But with chapter 4 the whole game went in a different direction... and considering that, the dark approach out of chapter 1 and 2 doesnt really work anymore... Ocean could have kept the dark way of course and go dark in chapter 4 too, but changed his mind about it, so it was the right decision to change the other chapters too.
The really dark approach is not my thing overall, so iam thankful for the change. But i didnt criticised the game for it, my point was... with chapter 4 the dark approach of the early chapters didnt work out anymore and the game felt a little off because of the change of the overall "mood" during the game. So yeah, without the rework it would be kinda messy, and thats the reason why i didnt played chapter 5 so far. I want to see the new "complete" picture.
Nontheless, SG is easily in my favorite Top 5. With dark approach or without.