I have been following this thread for a bit, and I just wanted to put my two cents into the pile, since this seems like a safe place to do so!
I wasn't very excited for Sims 4, namely because of all of the lag and optimization issues associated with Sims 3. The Sims 3 was a game I wanted to (and did eventually) love, in spite of its flaws. Though, I felt like The Sims 3 never really had a very good foundation, and with the addition of expansion packs built on top of it, the minor issues became more serious. The cracks in the foundation showed.
I started to change my mind when I got my hands on the Sims 4 CAS Demo. The new CAS is a seriously powerful tool, and very well designed, imo. It took me probably a week to master the controls of pushing and pulling and adjusting, but once I did, I was surprised by how much character I could put into my sims! The base structure and organization of CAS shows me that they really thought about how to design it and build a better CAS from the ground up.
I am guessing that this new CAS is probably what cost us toddlers and CASt. If you look at how many options are available for just the young adult sims and how malleable they are in creation, it becomes pretty clear that a huge amount of work went into the creation of the new CAS. That same amount of options and malleability would have had to go into each life stage that required a different template. Not only that, but all of the association required between features saying this nose turns into that nose when they age up, etc. I think they kept teen, adult, and elder stages, because those life stages probably require the same or similar meshes/animations as the young adult stage. If they needed to cut a stage out from a work load standpoint, they would have had to cut out toddler or child. While I will miss toddlers, I can understand why they made this decision.
While CASt allowed for a huge amount of choices, each of those choices is something additional that the game had to remember while running. I do think this probably contributed to the lagginess of The Sims 3. While I will miss some of the choices, I feel like a lot more care was put into the hairstyles and clothing options/color choices in the new Sims 4 CAS vs. previous iterations. They seem to have gone for quality over quantity, and I really appreciate that. I no longer have to scroll through pages of ugly outfits to get to one that I like. I don't have to scroll through 90,000 ugly hairstyles with hats that I will never use! I can sort things by color and style, and I can use clothing from any category in any outfit if I remove the filters. These are quality of life changes that I feel were long overdue for the Sims franchise as a whole!
After seeing the changes they made to CAS to make it run/work/look better, I am really looking forward to seeing what they have done with the rest of the game! Ultimately I hope they were honest in what they said and that they have been working on the foundation of the game so it can be easily built upon with future expansions and stuff packs. I think this kind of forethought is very important and was, to some extent, lacking in The Sims 3. I also think there is proof they are doing this, what with allowing you to move any family to any new neighborhood, all while keeping your relationships/jobs/etc. intact!
I don't think anybody really wants to go back to laggy generational play, hour long loading screens, and games that became so bloated they were too big to save. If I have to give up toddlers and pools to fix that (hopefully temporarily), then so be it.
I know a lot of people have said they found the new the new sims too cartoony, but I think you can get a wide range from cartoony to realistic with the new CAS:
Not to mention how accurately you can recreate real people!
My Origin ID is Simsperience if anyone wants to see the other sims I've been creating in the new CAS! They are also posted on my blog, for folks who don't have the demo yet:
http://thesimsperience.wordpress.com/ All said and done, there are a few things I don't like about the new CAS. Such as, the makeup options could really use an opacity slider, as it seems your only options are full makeup or none at all. The darker skin colors don't feel warm enough to me, so I hope they modify them and make them less ashy. I also sincerely hope they decide to add in more color choices for skin, eyes, and clothes, as I already miss my rainbow sims and sometimes I want more color choices for outfits.