It's definitely easy to get carried away with nested subtasks, but my team finds them essential for precisely the reasons @Todd_Cavanaugh doesn't like them in #2 and #3 in his original post.
Our primary use of Asana is for an editorial calendar. We do this the way Asana recommends, which is to make the entire calendar one project, each content item a task, and each steps to create the content a subtask. The sections are used to organize content; in our case we use months, but some teams use publication stages (e.g. draft, final review).
The key benefit of using tasks and subtasks in one huge project is that all the tasks (which represent content items) appear on the calendar, and the subtasks do not. Asana is very inconsistent about whether subtasks appear on calendar views, and it should just be an option. But in this case it's very useful that they don't appear, because this way we can see that we're making Announcement X (a task) on Wednesday and Announcement Y (another task) on Thursday, without the clutter of "proofread 17th draft" (a subtask).
The assignee for the task (the content item) is the person responsible for overseeing the production of that item, but the subtasks (the steps to create the content) could be assigned to several different people. Thus, we actually appreciate that subtasks don't inherit assignees and due dates from parent tasks.
We've had over 150 content items for Q1 2017, about half completed so far and half on the radar. If we used separate projects for each content item, that means we'd have about 75 items in the project list for just content alone. The content items also wouldn't appear on one calendar unless we used tags and a saved search, but then all the subtasks would also appear (see above re: inconsistent display of subtasks on calendar views). If we used one project for the content calendar but sections instead of tasks for the content items, the list would be impractically long because each section would have about 15 items. We also couldn't have discussion about one content item -- discussion would have to be about a step in the workflow.
It would be nice if the > symbol on the right edge of a task were more prominent. This indicator that there's something "behind" the task (subtasks, description, conversation) is very subtle and easy to miss.
I'd also like to be able to reorder subtasks in the mobile app. You can only reorder tasks right now.