^^You're certainly entitled to approach your family in your own way, but it's kind of excessive to assume that any family that's divided is somehow that way because one or both of its parents are deadbeats. What about military families? What about people who get married and have kids and then go off to serve in distant countries to make sure their spouses and kids remain safe? Are they bad parents in your eyes?
And it's important to keep in mind that in the Federation's political culture, exploration and scientific research are regarded as being as instrumental to national defense and integrity as combat capacity is. There's a reason that Starfleet performs both national defense and
exploratory functions: Because it is predicated on the idea that you need both to preserve the Federation.
So going off on a ship to be an explorer is, in the eyes of Federation culture, as valid an act of national service as going off on a ship to engage in combat.