The thing is the 4 child aspirations match the 4 main groups of adult skills. Unless they add corresponding skills to the adults, or revise how they are divided, they can't add another aspiration to the kids.
At the moment:
Motor Skill = Energized = Fitness (also effects vitality and metabolism)
Mental Skill = Focused = Logic/Programming/Gardening etc.
Creative Skill = Inspired = Painting/Cooking/Instruments/Writing etc.
Social Skill = Confident (and later) Flirty = Charisma/Comedy/Dancing etc.
The categories work, and if you choose just 1 or 2 you could have your child sims working on their preferred adult skills, rather than trying to complete all 4 and not taking advantage of the skill boost early on.