In Witcher2 the game offered you basically only two paths/stories which you had to choose one of it (and ofc you have replay both paths if you wanna see everything). Its a cool design, but I think its the easier way to make an RPG (and I wouldnt call it "hardcore") as when you go for constant changing of one story and the outcomes of events in it based on yr previous decisions.
I think that some people just don't understand how RPGs work and how choice and consequence system can be designed.
There is a difference between choice based on reactivity and choice based on branching paths, obviously though many games also attempt to combine the two.
Generally a quest branches will involve 2 or more routes that take you to a different ending, the quest will present to you at some point options to allow branches forward, so lets say you will get 3 exact branches that each lead to an end.
Alternatively a game could present to you a goal, tell you hey we need to go from this to this and its up to you how you do it, generally the game will react and present variations to you to achieve that goal, you could end up with 20 possible ways to achieve that.
In Witcher 2 case, when you reach the end of Act 1 the game presents to you a choice, you go with Roch or Iorveth, that takes you to a different chapter, but if you pick A or B your experience will always be the same, on replays you will either do A or do B.
In BG3 case you get a quest called deal with the Goblins, how you deal with them its up to you, you get a lot of possible ways to deal with them, the end ofcourse is that you will deal with them, but the entire process going from Start to Finish can vary, this makes replaying the game fun because each time you can do it differently. This will be illustrated if you give the game to 100 different players and watch them, its very rare to see 2 players doing the exact same thing to solve the quest, meanwhile in a game like Witcher 2 assuming the choice is 50/50 then 50 players will have the exact same experience.
Speaking of Evil choices making sense i'd say the Durge playthrough is a perfect excuse for all the horrible things you can do in the game, since you are technically roleplaying as Bhaals chosen, and siding with a cult, or a tyrannical leader or lord of murder is in fact actually evil.
For me the most fun evil paths are in Fallout games, those games are entertaining if you want to roleplay as evil person, i rarely play fully evil though, i just roleplay, i don't decide before hand that now i will roleplay 100% as this or that, i just roleplay how i see it fit, thats way more authentic that putting arbitrary roles on myself by saying i shall be le evil for the heck of it.
At the end of the day there is no set in stone way to design choice & consequence in a RPG, you have more than one way to do it, the most important thing is to do them well.