It's a bad idea, but if you want automated access it's the best we've got. Ideally banks would provide a nice API, but without a good enough reason they're just not interested.
The "nice API" comment is something that struck me after using mint for a couple years: there are banks/brokerages out there who are set up for this sort of thing and handle it well: tokens, revocation, etc. (Interactive Brokers is one.)