Good news, this feature is partially done. :)
Planner tasks can now be copied to other plans. To copy a task, click on the “…” menu on the task. From there, you can select a different plan to copy the task to.
-WarrenQuite irritated commented
What a stupid application that we pay a lot of money for!! There's no drag/drop option and notes and other data i not copied. There should be a MOVE and BULK MOVE option. Really Microsoft?????