You may be right, but that doesn't prevent them from using those same rights for other purposes (much like TSA searches being used to find drugs rather than terrorism).
If Google really means it, and wants it to be clear, they could put it right into the TOS: "Google may do X, when it does so in order to provide feature Y".
Let's say Mark Zuck. wants to use Google Drive, and upload all Facebook code on it. Using this TOS, it allows Google to go through the Facebook code, and use it to improve Google+.
As a programmer that uses Dropbox to backup all my code, I find this a little bit scary.
If you are concerned with storing your code on a service, perhaps you shouldn't store your code on that service?
The way I see it, they could go through your code and use your secret sauce, in secret. Now, with these TOS, let's say they are in the clear, legally. Now weigh the punishment Dropbox would receive for breaching your copyright, vs the punishment they would receive for using their users'/customers' data immorally, for their own gain.
There's only one word I have issues with in the entire TOS, and that's "promoting". Basically they can do the same annoying thing Facebook does when they use your face to recommend pages to other people. Google could potentially use your stuff to build ads for Drive.
These are the same types of arguments that a few of the more vocal but ill-informed professional photographers out there use to spread FUD about photo sharing sites like Flickr, etc.
The bottom line is that you, as a user, have to grant such a license to Google, Flickr, etc in order for them to be able to provide the services that you want. Its a copyright issue, and I haven't seen any other good way around it in anyone else's TOS yet and I've read quite a few.
If Google really means it, and wants it to be clear, they could put it right into the TOS: "Google may do X, when it does so in order to provide feature Y".