The Galaxy-class was a starship built for a different time. A time when there was no Borg, no Dominion, the Romulans were back in hiding, the Klingons were our new friends, the Ferengi and Cardassians little more than an annoyance. A time when it was thought Pax Federationica would last forever and Starfleet could handle whatever was thrown at it. A time when it was thought safe to include whole families on starships.
In short, they were 24'th century equivalents of 1960's muscle cars. Sleek, stylish, made you feel good riding it...and totally unprepared for the 1970's.
Frankly, by the time the Dominion War was over, I would seriously question the sanity of Starfleet Command if they didn't decide to cut their losses and phase out the Galaxy-class.
i actually believe the opposite...
i agree that the Galaxy class ships weren't prepared for the Dominion / Borg / whatever wars... but by the time the wars were over, when exploration was back on the menu, i'd say having families on ships like the Galaxy class style is a definite bonus for the federation...
if i'm serving in Starfleet, and they give me the option to go on a galaxy-esque class ship, or a normal no families allowed ship... hell, i'd take the family style ship any day... having families along on a vessel that could take you years, perhaps more, away from your family and out into the far reaches of the galaxy is a definite bonus for moral, experience, it would push the serving crew members with families on board to work and focus on the ships survival in a combat situation... i'm not saying there aren't dangers involved, of course there are, but if the option is there, i'd say the benefits far outway the drawbacks...
M