Hi Adam,
Why do you feel the need to Save To... all of your images - why not consider what's in Lightroom CC the completed image? Despite the "Save To" name, this is really meant to be used when you need to send a copy out to the outside world. (That said, there are always legitimate exceptions to general rules.)
I do think that the lock idea is one worth raising with Adobe. You can request this feature here. In the meantime, keep in mind that since Lightroom works nondestructively, never touching your original image, any and all edits can be undone, now or 5 years from now, so accidental editing at least isn't fatal.