The problem with charging people for password resets is that by making the process of resetting a password more expensive, you've now encouraged people to reuse passwords. People know when they sign up for your service that resetting a password is going to be expensive, so they'll use a password that they're sure not to forget, i.e. the password they use for everything else.

I would posit that even with this social engineering exploit, Google's two-factor SMS authentication is still more secure than charging people for password recoveries (and thus encouraging password reuse).