It would be useful if there was a toggle button on every view that can show items either from the current level or all levels below in the hierarchy.
E.g., if you are on a goal page, the toggle button would allow you to just show tasks for that goal only, or also all tasks for all sub-goals underneath.
This would be much quicker than having to set a filter for each sub-goal that you want it to show for, and would also mean if you add more sub-goals, you don't have to remember to add them to the filter.
The same is true for life areas as well, and in the future, subtasks when they are broken out into full items.