This is clearly a very hot topic in the community. Yes, subtasks are imperfect. No, Asana does not have to change the way it was built just because you want to. Does Asana wish it was easy to change the way subtasks work but does the legacy they have prevent them from doing so? Probably.
The community never fully agreed on best practices and bad practices. What I know is that many people are unhappy, and millions of others use subtasks every day and get along with it.
According to me, when to use subtasks safely:
personal checklist for the assignee to remember all the steps to go through in order to complete a task. e.g. Organizing a meeting requires booking a room, create a calendar invite, and prepare an agenda.
store an action directly related to a task. e.g. A meeting task could have a subtask « Send the recording to everyone ».
When not to use subtasks, or at least be aware you’ll probably run into issues:
store tasks that should count in terms of work being done. e.g. Workload does not show subtasks.
create subtasks assigned to different people with different due dates. Over time, this will make it harder to understand, and projects will lose clarity because work is hidden.
use a subtask instead of a task in a regular project. e.g. requesting a design as a subtask rather than going through the design request process (using a Form for example)
use subtasks instead of turning tasks into projects, because you fear having too many projects. My opinion is that many projects are better than many subtasks.
Did I miss anything? Does anyone disagree?