I agree with all of this. I've played Sims FreePlay for years, and despite my many problems with that game, one thing it did have was good babies. They could crawl around, learn to balance on sofas, and even have hobbies (the FreePlay equivalent of skills). Even without personalities (because FreePlay had no kind of personality system), they managed to be fun to play with and vaguely realistic. So, if they added that to Sims 4, I would be pleased. Also, I need to be able to make them in cas. I'm making a save file at the moment, and if I want to give any of my families a baby then I need to play the household for three to four days. It's getting irritating.
I figure that if they did have traits, they'd go off of the same trait system as toddlers. So they'd gain a pre-existing 'toddler' trait as a baby, keeping it through toddlerhood, then discarding it as per usual once they become children. I say this because the toddler traits we already have will work well for babies as well - or at least, EA isn't gonna waste cash on a whole new trait system.
In terms of learning and stuff, again I want a similar system as toddlers - I loved the way they went from babbling to talking as their skills progressed. Heck, I wouldn't mind if babies aged up based on skills - like once they could walk and knew a few words and stuff, they'd age up to toddlers. I want to play a little baby learning to sit up, then grab, slide, crawl, and finally toddle.
Edited out the rant about Sims FreePlay. I like that game, honest.
