Started watching DS9 and I have a question. Why was Jake and Sisko's wife in the ship during Wolf 359? IIRC Wolf 359 was the last standout between Borgs and earth so it really wouldn't make sense to bring your family with you knowing what's ahead.
Star Trek has always said that starships are sent out on multi-year missions. The crews are stuck on the ship with maybe some occasional shore leave. TNG suggested that some fool within Starfleet thought it would be a good idea to allow people to bring their families on board, so families wouldn't have to be separated for years at a time. Maybe it made sense because Starfleet in that era was at peace with everybody, even the Klingons. Picard notably thought this was a bad idea. The Enterprise-D seemed to be a test case for this idea, since it had the ability to dump it's civilians off in the saucer section for safety.
At some point, Starfleet thought it was safe enough, so they stopped designing ships that separated, and they allowed families to board any old ship.
Starfleet didn't have time to put together their defense against the Borg. They didn't have time to offload non-essentials. The Enterprise-D didn't even make it to the battlefield in time to help.
The real mistake was that Sisko only ordered the civilians to board the escape pods after his ship's destruction was imminent. But I guess that "battle stations" for a civilian means to go to your quarters and keep quiet, not to climb into an escape pod and wait for your side to lose the fight.
Edit: Yeah, thinking about it, when the ship was ordered to the line, they definitely should've put all the civilians into the escape pods and launched them behind the line towards Earth. Pick them up after the fight. It wouldn't have disturbed the ships battle-readyness.