And how many times has this actually happened in real life as opposed to the internetz?
The only thing "older" than the semi-snarky "well, enjoy my 4 year your old sitting next to you comments" ON THE INTERNETZ are the "I *paid* for my seat assignment, if you need to sit with your children you need to pay (through the nose/fly another carrier/yadda yadda yadda) to book so that you're guaranteed to sit with your family" (also on the INTERNETZ.)
Aw, heck, as long as all this silliness stays on the INTERNETZ, I don't really care. On both my flights, all the SW customers - us included - who booked with points were all intermingled and worked things out to everybody's satisfaction with smiles and friendly conversation. (This included one mom who didn't really care about sitting with her husband with lap baby and her older son. She had a great conversation a woman and her daughter behind us and we happily passed clean diapers to Dad when necessary.)