The problem with the attraction system for me in the past is that I like to have full control of my sims. They always ended up attracted to everyone expect the sim I had planned for them. Sure, I was still able to get them together, but the story I had planned in my head just didn't play as smoothly. Especially in TS3 it felt totally random.
An attraction system based on traits might make sense at first, except that sometimes opposites attract. A tidy Sim might have a lot of arguments with a slob sim, but that shouldn't necessarily mean they don't feel attracted to each other.
