Agreed. It should be almost as simple to create a sub-task (of any task) as it's to comment. Also convert a comment to sub-task. Browsing is another problem...
And there a fundamental impedance mismatch between these tools and actual work rears its ugly head. Work is structured as a dependency graph - a DAG. To complete C, you need to do A and B, but a part of B depends on a part of A to be done, etc. Yet these tools insist on a list, or a very flat tree (a task and maybe a subtask, but no sub-subtasks).
