I think games like Phantasy Star 2, Star Trek Online, and Saints Row the Third really set a good standard for character creation, and while they weren't perfect, they were steps in the right direction. It might be entertaining to have a tall, anorexic sim, or a short obese one, or any mix inbetween. If limitations are set, they should only be done within reason, but we should be able to make our sims essentially as small or as big as we want. In the real world, people come in a gigantic range of shapes and sizes, rather than a set frame with slight variables, and I think that should be the same for the Sims.
This is good, because being able to create a sim that's uniquely yours is important, but my only concern is how limiting will it be? For example, Late Night introduced bust sliders to the CAS, but it seems like the size stops off at DD(unless you mod, and then they don't even look right), so I think with these sliders there should be a much larger range of sizes to work with, not just bust, but with everything else. So with some of the teaser images, it's suggested that we might have a wide range of sliders with The Sims 4, with things like height, arm length, arm thickness, hips, etc.