Why is it necessary to punish players for missing Vana'bout objectives?
If failing to clear a Vana'bout objective one day means a new one is not given the next day, this is a punishment for the player. If they are for some reason unable to complete an objective, they lose not only that day's plaudits, but the next day's as well. This is hostile design.
The objectives should simply be replaced each day unconditionally, if holding an objective from one day must necessarily mean not being able to obtain one from the next day.