Turn off Google Drive Preview "Feature"

You cannot. In general, for better or worse, Google does not present features and allow end users to select them based on whether they want them or not; the same has happened with the compose functionality in GMail, the recent changes to Circles, and a number of other features and functions in their products.

I don't think so (although I should say that I think the new preview function is better), but on the bright side if enough people complain about the change, Google may do something about it. For example, with the Chrome browser, for a while the home screen displayed a wretched, virtually non-functional version of the Search home page, squishing down all of the the app icons. Why? Because not enough people are using the "omnibox" to search Google directly. But it was a dumb decision - the various Google animations that don't really interest me are not even animated on the Chrome home page, and the Search results page was terrible from a usability perspective. After a week (and presumably lots of complaints) the feature was removed. So don't give up help!

KokuRyu, can you explain what the advantage is to this function? Maybe if I understood how it was supposed to work, I'd be a little less irritated about it. Because in my mind, all it does is make documents harder to open. Does it also do something useful?

I'm wondering if we use it for the same purpose. In my experience, the Google Drive document viewer was a quasi-pdf way to view non-Drive file formats, notably .docx. You couldn't edit them within the old viewer, and they looked terrible. With the new viewer, non-Google-format documents (.docx, etc) are presented a little more nicely, and can even be more easily edited withing Google Drive. They have also adopted a G+-style interface for downloading and sharing. The regular Google Drive editor still works fine...

Maybe I'm still not understanding. What's the difference between the "document viewer" and Google Drive? When I use it, I go to drive.google.com, and it gives me a list of all of the documents I've created or saved there. I used to be able to click on one, and it would open, and I could edit it or print it or share it with someone else. I have lots of .docx files that I could edit with few or no problems. Now, I go to that URL and click on a document from the list, and it opens it in the preview pane, meaning 1-2 more clicks before I can actually use the document. Am I missing something?

I'm not sure. I can't recall when I was last able to easily edit .docx files in Google Drive. If I upload a .docx file to Drive, it's always presented itself in a document viewer of some sort. Sometimes I am able to convert the .docx file to Google Drive (or Docs) format, but the formatting all goes to hell. Drive is useful for storing and sharing .docx files though, and you can also also track modifications to .docx files. So I've always had a document viewer of some kind that has been tough to use. On the other hand, I create a lot of documents in Google Docs/Drive format. These open easily, and can be edited easily.