People might remember the 'Civilians stay indoors' command that used to save many a sieged fort. Somewhere along the line, though, at least for the Mac version, this has gone missing, or at least is no longer in it's old place.
Just today, I had a siege that went spectacularly badly, not due to a lack of planning on my part, or anything else that I consider to fall into the same 'losing is fun' thing, but because, when my first military dwarf died, a handful of civilians ran out to gather his gear to take it to the stockpiles. They saw the goblins (and their beastly companions) and did the normal job interrupted thing, but rather than actually go back in the fort, they ran around randomly on the surface, where the goblins picked them off, along with the repeating waves of dwarves coming to gather up the dead military dwarves' gear. Before I successfully broke the siege, 3/4ths of my fort had run up onto the surface to be picked off. The remaining 4th was primarily injured dwarves from previous raids, and mourning friends of the civilians that, if the command was still around would never have died in the first place. As I speak, I have 5 functioning dwarves, where, pre-siege, I had 150 dwarves. I have 30 in total, but most are children, berserk, insane, or injured. All because 'stay indoors' disappeared.
I get that a lost fort is part of the game, but when it's some quirk of code that causes my loss, I feel a little cheated. Similar to a abandoned world where my fort ran into a functionally immortal bronze colossus. I gave up after the dwarves had been fighting him for 3 months to no effect.