Yeah, I remember that Voyager ep. I didn't count it because it was a tactic they intentionally used offensively - they fired the torp planning to detonate it with phaser fire.
But we never see a ship, even once the shields are down or are useless (such as Generations) actually fire at a photon torp trying to knock it down. Plasma torps, yes, but never photons. Considering the number of times that would have made some type of tactical sense and assuming guys like Riker, Picard, Sisko, and even Janeway aren't complete morons, there seems to be a reason that they don't.
But we never see a ship, even once the shields are down or are useless (such as Generations) actually fire at a photon torp trying to knock it down. Plasma torps, yes, but never photons. Considering the number of times that would have made some type of tactical sense and assuming guys like Riker, Picard, Sisko, and even Janeway aren't complete morons, there seems to be a reason that they don't.