Yes!! The memory system in Sims 2 was simple, but so effective. I vividly remember the first time I played the Broke family, and I glanced at Brandi's memories, and it told me her husband had a pool ladder accident. Those memories make your Sims' lives unique, add to their personalities, help you tell more detailed stories, and may even affect how you play that Sim!
I also think memories (because we are in TS4 now, so it should be better than TS2) should have the ability to change/add traits to your Sim. For example, if your child Sim specifically remembers his/her parents divorcing, they may have the "Noncommittal" trait added to their list. Now, obviously the Simmer should have SOME control over that (because not ALL people would become Noncommittal over a divorce--some might become Jealous, or even Romantic, a desire to achieve a love their parents hadn't), so maybe there should be a slew of options that you have to choose from.
Regardless, I think memories are so important, and many should have a lasting affect on your Sim.
