There are many factors that we don't either know or are capable of understanding. For anyone even sorta thinking how great it would be you must look at both sides of the coin. Dark Angel is the perfect example. ( a tv show on fox a couple years ago). But it pertains that she was always being hunted, never thought of as human. It may be great to have the super capabilities but not everyone is so open minded. Most in the US are even arrogant and judgemental.
When you modify a kid it makes me think of American Girl dolls. There's a kind where you can pick the hair, eyes etc...in my oppinion, totally making someone perfect takes all the fun out of life and our goals to learn.