I'd thought about this a lot, and was curious what others thought.

Back in the day, I never really minded the transition from personality points to traits. I thought the points system was more nuanced, sure, but traits still fit the Sims style quite nicely so I never really had an issue with them, and still don't.

However, a while back I remember reading Ray Mazza's (Co-Lead Designer for TS3) blog on how traits were developed for TS3. Specifically, this is what he noted about the perception of personalities coming from TS2 and what influenced the creation of traits for TS3:

"The problem we found as we were implementing personalities on The Sims 2 was that we couldn’t reasonably create enough special animation and interaction content to make each notch of the 0-10 scale feel interesting.

Additionally, players didn’t understand that there would only be a nominal difference between, say, a 2-point and a 3-point Sloppy Sim, but a huge difference between a 3-point Sloppy Sim and a 4-point Sloppy Sim. We didn’t make that clear in the UI, so players had to learn this from strategy guides and Sims wikis.
...
Around the time we began designing The Sims 3, I’d been reading a lot about screenwriting, and noticed that in screenplays, characters often have a few glaringly distinct traits. There’s no fuzziness about them. We used this approach as inspiration on The Sims 3, and developed a philosophy of doing away with the continuous aspect of personality. Instead, we wanted to take the extremes from The Sims 2 and package that fun content into discrete bundles of behavior."

The last part of that statement always rang as interesting to me. Taking the "extremes" of Sims' behavior and making them into "discrete bundles of fun."

But the issue I've found is just that. I mentioned at the beginning about personality points, and how they filled in the more nuanced portions of a Sim's personality. And ultimately, I still believe that to be the case.

That's also why I feel they could have worked well together instead of one vs the other. The issue with traits is that they're all or nothing - you either have a completely neat sim, or a slob. No in-between. They're absolutely fantastic though for filling out the more exaggerated parts of a Sim's personality, the individual quirks that make them unique that is. So, having them alongside personality points means you could have a defined overall personality, with the traits giving them character to stand out even more.

This is an interesting thought. It strikes me that perhaps the TS2 system was too nuanced and the TS3 system not nuanced enough. If you only have 3 levels of intensity that you can make visible to the user, make it a 3-point system. A sim can be mildly, moderately, or extremely Sloppy rather than Sloppy level 4.

Also, I don't think TS3 really solved the problem of invisible personality features. I think too many traits are expressed through idles and minor moodlets that just add or subtract a small amount to total mood. Most idles don't show up unless the sim has nothing queued. That never happens with micromanaging users, and even if a user leaves sims on autonomy most of the time, idles usually don't intrude on anything and are easy to ignore. Why do I care that my Sailor sim gets a +5 moodlet when they're on the water? This bugged me a lot with the disease/allergy system in Seasons and is the reason I wrote Symptoms for Seasons. In the code, Germy contagion and allergy genetics are fairly sophisticated, but why would you care when you barely notice you have either one?

I want a sim's personality to affect a sim's behavior and gameplay in a noticeable way.

This was my hope before TS4 came out. I like both systems and I thought a combination would add the more immediate behaviours caused by more extreme levels of a trait while keeping it to idles for less extreme levels.