A lot of players doens't have time to grind 16k XP every day.
In fact they might only be able to play a couple of days per week, but instead got lots of hours on those couple of days.
Changing the cap from a daily > weekly would mean more players can enjoy the game when they actually got the time to play instead of feeling they are constantly missing out on progression and almost feel "forced" to log of after playing a few hours during a day (Despite potentially having a lot more time on their hands on those few days they are able to grind)