TS2 townies and NPCs don't look or feel "just thrown together". They only lack family trees but everything else is there, their aspiration, personality, interests, hobby, memories, chemistry and, finally, relationships. That's a lot of factors and all together they form a very complicated and effective web. Make Goopy or any other townie/NPC in Pleasantview or any other 'hood playable and you will be surprised at what you will find; you will love it or hate it or anything in between, but you will certainly not be bored.
Zois have nothing like that. You may spend a long time perfecting their physical appearance but when it comes to their personality, you'll be done in a jiffy, and most of these factors (well, two out of three) can be changed later on without a cheat. The premade ones are, of course, no better: for a short time I played a Dowon family, consisting of a single mother and two elementary school boys, living in what the game called "a villa" (if that was a villa I live in a palace). No father in sight. She had a few friends but no lover; was she a widow or what? No idea but the situation was almost the same as with Brandy, and now think about all of her story. No competition, really.

Maxis put a lot of work into their characters, and it was so much wasted on me. I just didn't get them at all.