I do not think that XP based on rapid completion is suitable to RTwP games (if bg3 is going to be like that), it is more a TB thing or tactical games like Valkyria chronicles or Fire Emblem.
Even in games that use xp based quest outcome, not in enemy killing like VTMB you can have different xp rewards depending on how you complete the quest, skill usage, etc. ej: Not being detected, achieve a diplomatic solution, rescue all hostages alive, etc.
Yes, VTMB was also a great game in this regard. VTMB, Deus Ex, the original Thief and maybe some other games encourage you to play in a way that makes sense in the game world.
If there was an RPG that rewards you depending on how fast you play, I would not like it because I am a very slow player who likes to explore everything and actually read all these walls of text.
I am perfectly OK with quests like "You have to rescue the kidnapped person in 2 in game days or she gets killed.". In fact, that makes much more sense then the usual "You can take as much time as you want, everybody is waiting for you to arrive."
I think Pathfinder Lingmaker did it right: There is a time limit and failing it has massive consequences, but the limit is so large that you should not have a problem unless you rest after every battle or you chose to explore the entire map when somebody tells you to go somewhere now.
I don´t think that role playing and speed running fit well, unless you role play a speed runner. The result would be something like Mirror Edge, I guess.
Prof. Dr. Dr. Mad S. Tist 
