You hit the nail on the head about the difficulty of such functionality. If we are going to make such functionality, we want the result to be usable. If you need to do the same amount of work as when making for example a page from scratch, being able to copy a page will add very little for you.
We will add your suggestion to the list of ideas as it can be a nice addition to Triggre. However, because of the challenges this presents to us, it would take us some time to come up with a proper solution.