I believe that forcing the players to "act the way you want" is not the way to go and because there's no day/night timeframe/clock, it would take a significant rework of the application (per 5e you can only benefit from a long rest once every 24 hours). Like you mentioned in your post "You can successfully manage your resources and have several consecutive encounters in BG3 without being forced to resort to a long rest." which means that you tried that play style. I do the same thing on purpose, extend my time between long rests, because I like playing as if this was a PnP game. However, there are times when I've gotten my self into a jam and needed to have a long rest. Having the option of a long rest at any time, made the game more enjoyable for me. There are those that will "abuse" this option/ability but that's entirely up to them. As another example, there are MMORPG games where you would die and you can simply respawn. I've played in groups where the players would not respawn and either wait for a good samaritan to rez them and some groups that play permadeath (even though they don't have to). Leave it up to the players how they would most enjoy the game and not force them to play as you feel it should be played.