You're correct that it absolutely isn't free but the gall of Google to, once they have all the data, to turn around and demand additional payment for continuing to store all the data they sought out and that they've resold many times over - it's shameless greed at this point.

And it's isn't even like they're struggling with profitability, either. It'll be hilarious if this forces common folks to switch back to IMAP since once a user has been burned into spending the trivial cost to set up a local mailbox sync they're unlikely to go back into Google's arms (especially given how cheap (in money and time) disk space and cloud backups are these days).