But families have never been on military ships at sea.
As suggested, this has been a primarily logistical limitation. Even though really jam-packed (and because of it!), the old fighting vessels just couldn't have accommodated the number of people involved in functional family units. Officers might have taken their wives with them aboard the later, more luxurious vessels, but the resulting inequality would have caused giant discipline problems.
Ships of today wouldn't face actual logistical problems if some people aboard formed family units, as long as they didn't have any kids. The biggest ships of the Trek future wouldn't have a major problem even if a crew member decided he'd like to take his hometown with him. Starfleet might even consider that a prudent move in order to avoid homesickness...
Didn't the Enterprise D have Runabouts by this point?
The big lady has probably always had a greater variety of onboard auxiliaries than we were shown. But she has never used them for combat, apart from special forces insertion and extraction missions. Today's naval vessels don't deploy their Zodiacs when going to battle, either; incoming suicide boats are best intercepted with shipboard automatic guns rahter than with one's own boats.
I'm not sure a runabout or some other type of fightercraft would have been able to do much against the Jem'Hadar ramming attack. Note how the attacking ship moves so swiftly that the runabout trying to intercept it actually
misses with its phaser beam - a never before seen event in 24th century Trek history! If a phaser beam, with a standard hit rate of 100%, can't catch that bug, what hope would there be of positioning a runabout on the bug's flightpath?
Well, yes, once the Dominion became aware of the increasing influx of ships from the AQ, they apparently increased their own military presence in the vicinity of the wormhole.
Not enough to do anything about the Alpha presence, though - not until "In Purgatory's Shadow" anyway. The Alpha comm relay stayed there untouched; reports of Alpha ships arriving in Gamma never seemed to reach Dominion ears in time, either. One would think there were massive problems with distances and logistics to keep the Dominion from being more prominently in control of the Gamma end. Which was very good for drama in the end...
If, as I suggested, TNG had sent the Enterprise to the Gamma Quadrant for its last two seasons, then the storytelling needs of TNG might've limited whatever DS9 wanted to do with the Dominion. Or at least shaped it differently.
And it would have been a nightmare to manage. It wouldn't just be a matter of having to match TNG scripts with DS9 scripts for consistency (something that was only done twice or thrice during the entire runs of the shows - or with DS9/VOY when those two ran concurrently). Worse still, both shows would actually have to
preplan these things, at least one season's worth ahead, whereas neither of them actually did much preplanning as matters stand.
Timo Saloniemi