I imagine those of you who understand all this are getting fed up explaining it. I tend to put it like this....
When you created the family, the game created all sorts of bits and pieces of data about the sims and the family and stored info in a number of different places in the neighborhood package and character files. While the sims are sitting in the simbin, the game creates more bits of data about them. The maxis deleting tool doesn't find and delete all of the bits. Why take a chance on one of these bits of stray data biting you on the ass later? Don't sweat the detail, just use the nice safe tool Pescado made for us. Those of us who got the Tshirt for messing up our hoods by deleting sims and cleaning up badly, don't recommend that route to others!
Hmmm...so if I'm playing around in CAS and creating lots of families that are
not saved, or I only save one or two of the sims I created, am I generating a bunch of useless bits and pieces of data to clutter up my game? Or am I okay because I don't save them? Is this anything to worry about?