Within a Project, you can create Sections. The sub-tasks of those Sections should be collapsible/expandable. Those subtasks can also have their own sub-tasks, and they too should be collapsible. These sub-tasks should be tabbed in from the “parent” tasks. Creating sub-tasks should be as simple as pressing , or perhaps <Tab + Right/Left>.
I was just about to submit this request and came across yours. I second this. It would also be very helpful to have this in your own My Tasks as well!
+1 on collapsible (and indented) subtasks in list view