So, the reason for this suggestion is simple:
It's a new trend to, instead of making "daily" missions that reset on... reset, they have a fixed 24h cooldown.
In practice, that can make said missions have effectively 48h CD instead.
What happens is that the timer starts to run after you complete the quest.
So let's suppose you start playing 19h, and you have 2 hours to play in your day.
You pick up your "daily" (24h cd) mission, and go finish it. 2h later you finished it.
What happens next day? You can't grab it until 21h. You can't really do it. So you'll pick it up, and stay with the quest until the next day, where you can play again to finish it.
And the cycle repeats.
Now the quest, instead of having a 24h CD, has effectively 48h CD. You'll be doing it only once every two days.
Making the quest reset in 20h instead would "fix" this, making it possible to actually do it daily, without having to always drift to later and later times.