My favorite way of playing Sims is to create large families and let the Sims take the lead on character development, relationships, etc. I like free will and always randomize traits (and sometimes aspirations, unless they have a personality well-suited to a specific one). My favorite point in any Sims game is after 3-4 generations where there is a massive family expanded all over that particular universe, and I am really happy that Sims 4 story progression allows for non-active-household Sims to get on with their own lives and go in their own direction. In Sims 3, I was constantly having to progress other households to keep up with the family members (i.e., make couples get married, have children, etc.).
My current Legacy family is at Generation 4, and the Founder boasts like 16 great-grandchildren so far. They're totally taking over the neighborhood and I love it!
On a psychological level, this might be because my extended family isn't particularly close. Whoops.