I like them as they are. I like that they can learn to walk and talk by themselves over time and that they aren't quite as dependent on the parents to learn things like walking, potty training and eating.
What I think would be better is for the baby stage to last longer and have some kind of visual progression like we have with babies in real life. A baby will start out as they do now but eventually they grow into more active babies that can leave their bassinet, sit up and even play with simple toys but they still rely on the parents for everything such as feeding, cleaning and diaper changes and they will eventually progress into a crib for sleeping. In real life there is a huge difference between a newborn baby and a baby that is a year old but it's still is a baby. Sims 4 and all the previous versions of the sims do babies so badly. They aren't just inanimate objects in real life. The problem is with babies not toddlers.