I guess it would have been a much more powerful device in Sauron's hands... but that's the classic "we find some amazing new tech, then declare that it's wrong and the best thing we can do is to stay where we are" story, found in lots of sci-fi stories. (There surely is some tv tropes concept for this...)

By the way, the Ring is even cooler than that... see HPMOR chapter 64 (or is this Reasoning from Non-Canonical Evidence? :P)

(edit: ch. 64 is Omake files 3 with non-HP fanfics, so I really really hope it's free of HPMOR spoilers...)