I think that we need to educate new geocachers on what Trackables are rather than restricting Trackables to Premium caches. There are many experienced cachers with free accounts that haven't made the switch just yet.
I would recommend to geocaching.com to limit Trackables to people who have racked up a certain amount of finds. Alternatively, people could leave a note attached to their trackable (similar to a finder's note for muggles) explaining what a Trackable is or at least the importance of not moving the Trackable if you don't know what is.
I agree with several of your points but I think that it is up to Groundspeak to make a plausible solution that doesn't exclude cachers. Putting trackables in only premium caches is one step towards making Geocaching a paid hobby- something that will not attract new cachers.
