I realize this will be a bit complicated to implement, but this feature would be really nice in some cases.
It’d be nice if a parent task could fill in its value for an attribute by aggregating the values from a subtask. For example, sum up the number of story points of subtasks, generate a due date based on the last due date of a subtask (or the first!), etc.
Bonus points if this behavior could be standardized on a list so that it was the default behavior for all parent tasks with no value set, so they would adopt the default aggregation behavior unless a value was put in to override it.