[Update] Disappearing Hot Time Box Rewards

Hot Days were put in place to incentivize people to play.
RED is serving as that incentive right now. There's no need for hot days.

If you read the Update Notes and Event Notes you'd see that there are already three Hot (Cool) Days planned for December, and probably some in the works for January. The reason why yesterday was a Hot Time is because the rewards were way too good to allow people to get them on many characters; I doubt they're planning to switch back to Hot Times generally, since that causes problems for both players and Nexon.