Why would it make you dislike Picard more? He had no control of his actions while he was a Borg Drone. Sure its easy to see why Sisko would be upset but IMO his anger should have been with the Borg not with Picard.
We were experiencing something rare for a Star Trek series: a character who experiences an irrational emotion and just goes with it anyway. Characters from TNG too often experienced "appropriate" emotions, or had enough self-knowledge and ludicrously healthy coping skills that they were able to quickly diagnose their own psychological blind spots with ease (and a little help from the ship's counsellor).
Sisko was just being your typical complicated human being, so filled with rage and hopelessness that (justifiably or not) Picard was a perfectly natural target. Hating the Borg and anyone even vaguely associated with them was convenient because Sisko was completely unprepared to deal with his grief over losing his wife. Calmly explaining this perfectly logical fact wouldn't do any good, just like with real people.
Once his encounter with the Prophets forced Sisko to confront that grief, Sisko was later able to see the irrationality of his anger with Picard. IIRC, there was a coda between Picard and Sisko where Picard told Sisko "Good luck Commander", and Sisko replied "You too, sir". Something like that. The subtext of that scene is that both men saw in each other a shared loss because of the Borg. Sisko was able to forgive Picard and empathize with his loss.