I stand by what I wrote.
This isn't a videogame; sometimes the best you can do is concede defeat and do damage control. That should not be confused with success.
Vulcan, according to your logic, HR mission is a success if there are 600 casualties, and one survivor.
Success or failure isn't a matter of bodies along the lines of "Well, 115 is a success, but 200 would be failure". Success is quite simply eliminating the effectiveness of hostage-taking, so the state emerges with a strong public image, and future hostage-takers are deterred.
In a totalitarian state, this is easy. Someone takes a theater? Black out the media, and only rumours are heard. Then you can do whatever you want to the hostages and the hostage takers.
Here it's not so easy. Lessee, someone takes a theater, threatens to kill 600 people (and sorry, bystanders outside the theater are not in the terrorists' control, and shouldn't be there) unless certain demands (which everyone knows will not be met) are met. So they get news headlines for three days, and in the end, 115 hostages are dead.
What's the difference? 485 people. A statistic. There are still a lot more innocent bodies than hostage-takers. The difference in media impact between 115 and 600 people is minimal. This isn't a dozen unfortunate casualties, it's three times the number of terrorists.
And any logic like "well, they let innocent people die because they were afraid that maybe the terrorists would come back next month" is stupid. They'll be wearing gas masks next time.
Success may have been impossible, but whatever it is, it doesn't involve meeting the hostages' threat.