Why is there still only 3 trait slots?

I wouldn't mind 5 trait slots - or, more accurately, two more per age group. The reward traits are nice, but they aren't really character defining. I think I saw something (don't ask me to find it, it was on twitter) from one of the Gurus that there's no technical reason why they can't add more, they just haven't had a project yet where they could logically incorporate adding more slots into the requirements. But I may be misremembering/misunderstanding what they meant.

Now, the traits should also actually have more impact on the sim's autonomous behavior rather than getting buried under emotions all the time, but that's a different issue.