Sooo Why cant unplayed sims make their own decisions (Marry,Children and Dating)

If you want families you don't play to have babies and stuff go to household management and add some kids into their household (preferably using the 'play with genetics' option so they actually look like the parents). It's not ideal but it works. I have townies who are the grandkids of the townies my game started with, which feels a lot nicer than the game continuously adding random strangers with no connection to anyone to the population.