People don't like time constraints, no matter how forgiving they are. Many people will feel compelled to rush, which spoils the gaming experience.
Personally, I don't want any time limits, I like to play the way I want and not be forced to choose the most optimal path or worse, intentionally have to avoid certain areas as long as possible just to not run some script that starts the timer.
Fortunately, game developers know that time limits are not popular and do not try to force them into games.
People didn't like Kingsmaker time constraints (most of them at least) which ended up with WotR literally having one time quest.
