I have thought about it, but allowing for that would require some type of user authentication system which would increase friction when it came to onboarding. If I decide to go with user authentications, then I think adding comments is a no-brainer.
Only require authentication when the user wants to make a comment. You could also use Facebook/Twitter login systems built into the device so the user presses login, selects their account from an action sheet, and they're in. No username/password friction.