It is an extra level and I would use it. The person above says old tax docs aren't interesting. They arent, but they are a gold mine for identity theft.
Sure, but it's not like you're putting them out on some random webserver for someone to find. Google Drive, Dropbox, etc, when protected by two factor auth, is really quite secure.
If you're worried about Google stealing your tax docs to use for one off identity theft... I guess encrypt them? Or just don't use Google. But I don't worry that much about them making use of random documents I've uploaded.
If someone wants your stuff, specifically, they can probably find a way to get it, and locally encrypting it doesn't matter that much (if they've compromised the endpoint, they can just wait until you decrypt it or encrypt something else, sniff the keystrokes, and go at decrypting it). But up on Google Drive is a secure place that's defended against random attacks, even if someone guesses your password, because you've got the second auth factor in place.
Given a reasonable threat model for the situation posted, I don't see how an additional layer of encryption adds any useful protections.
