Reading the rest of the thread, it looks like Apple is already saving you from yourself by creating a revision each time you save. So, this change just increases the amount of work the user has to do by forcing them to go and revert the last save on the orignal document after doing a Save As.
People using "Save As" frequently don't know that they want a duplicate before they start changing things. Sometimes what I think is going to be a minor change ends up being a major change, and I want to "fork" the document.
Think of it in git terms:
I start a changeset, and after some work, find that the changeset is too big or too unstable or too hard to merge upstream. So, I `stash`, `checkout new-branch`, `stash pop`, `commit` (or just `stash && stash apply`)
This new workflow is effectively: `commit`, `checkout new-branch`. Crap, now my unstable changes are committed to my master, and to fix them and get back to what I was working on, I have to `checkout master`, `reset --hard HEAD^`, `checkout new-branch`.
It's annoying and presumptive. If git did this, there would be rioting in the e-streets.
