"The engine doesn't have it" is a poor excuse, because no engine comes with the "day/night cycle button" and it's always a matter of implementing it.
It should also be none of our business to worry about how much work it can be to implement standard features in the genre, but that's another topic for another day.
I know it is. That's the point.
They didn't program the original DOS engine with this feature and now they might not want to do it because it's hard to do. Same with implementing reactions and readying actions. Either this or like anything else, it's their "vision" and these features would make the game worse.