Making new animations for another sized frame would be too expensive for a decade old game. There is also the fact that making new CAS assets for another frame would just add more cost. So, there would literally be ZERO benefit.
You can already do that with your imagination through gameplay mechanics anyway. On a normal lifespan, the child stage is 13 days. You can dress them very childish and limit the skills in such a way to "simulate" age 5 to 9. After about 7 sim days, you can go into CAS and dress them more pre-teen like and extend the gameplay to simulate age 10 to 12. You can do the same in the teen lifestage, but since that lasts 21 days, you can go into CAS twice for the age transformation through clothing and each sim week extend the gameplay you allow to simulate getting older. That is what I have always done since 2016. I did have to realistic my gameplay to allow for the extra 7 sim days added after High School Years ep.
Making new sized frame would not be too expensive mean did you forget they added both toddlers and infants to the game both different frame from the rest of the lifestages and they are totally different frame from each other, Also the CAS for both infants and toddlers are different. So your explanation is flawed when there's literally proof with both infants and toddlers with different frames were added to the game.
Now at the start of the game I would have agreed however since this game have progressed I don't agree it was just a half baked game back then.
