TNG was apparently developed by "solving" every problem that TOS supposedly had. Especially the problems David Gerald pontificated about in The World of Star Trek. The captain shouldn't beam down to potentially dangerous places. He shouldn't be a hit with the ladies. Blah blah blah. Gerald probably said families should be along for the ride, or that was a GR thing.
GR started this whole thing with his insistence in The Making of Star Trek, "Why should a man give up the joy of ham and eggs if the technology of his time permits it?" or some such. And then, given time, this kind of space-luxury thinking ballooned into the captain having his therapist on the bridge and civilian spouses and children being aboard. Jeez.