According to the quoted story, Reddit's activity was responsible for the release of the images earlier than they'd planned to release them (if ever). That's not "worse than useless," it's actually quite useful.
The reports from law enforcement involved in the firefight is that the suspects had an entire arsenal of improvised explosive devices. If they had not been killed or captured, there's no reason to assume they wouldn't have been able to hit more targets. Indeed, that may have been what they were doing at M.I.T.
Yes, it's possible (though not likely) that the release of the pictures had nothing to do with the rash actions they took. It's also possible that if the pictures had been released earlier, their actions would have been even more rash, and more people would have died.
You're not going to stop people from trying to help solve cases like this. The social media genie isn't going back in the bottle, short of a draconian limitation of rights that neither of us would like to see. I suggest that more openness, not less, is the preferable course.