What is the reasoning behind the design of not inheriting the SCHEDULED and priority properties?
Any notable use cases to support this behavior?
On the contrary, actually inheriting SCHEDULED (or DEADLINE for that matter) and priority properties makes perfect sense to me.
For instance, if an entry is SCHEDULED and thus is appearing in the week agenda, adding a sub-item to it will automatically bring that item to agenda replacing the parent. This will prevent the parent from falling out of attention. In the current design you may loose a DEADLINE task forever by adding a sub-task to it without scheduling it.