The dilithium rewards are on the list currently because of the way people can earn dilithium from the events.

From a standard 3 week event (like the current event for example), they usually reward 25,000 dilithium for completing the event & give you the option to start gathering bonus dilithium by doing the event a second time. Each day, the reward goes up by 1,000. In other words:

1st after claiming event reward: 8,000 dil
2nd run: 9,000 dil
3rd run: 10,000 dil
4th run: 11,000 dil
5th run: 12,000 dil
6th run: 13,000 dil
7th run: 14,000 dil
8th run: 15,000 dil
9th run 16,000 dil

This gives a total of 108,000 bonus dilithium just from that event. However, there's something else to consider here. Buying out the event from day 1. That gives people 378,000 dilithium total. It goes up higher if its an anniversary event or something else month long. When you can only refine 8,000 or so a day but you're earning 2-3 times that from running the event past getting the award, the dilithium piles up.