Well, I haven't heard of Willow Smith myself... but it is quite obvious that she gets a fantastic backwind by having parents like Will and Jada Smith. She gets easier access to pro people, the attention is already there, and so much more... but I guess in the end, she will only remain on top and popular and in success if she actually creates something of quality. Once again, it is easier with parents like that who can help her and have contacts and who can make some calls for you... so she has a gigantic advantage compared to many others, that's for sure.
But, I must admit... it can for sure be tough to come with parents like that, because everyone will always point at your parents and claim that they are the key to the success, and stepping out of such a shadow and actually stand on your own legs and feel that you are someone yourself without your parents petting your back, that can be tough as well (even though it is a blessing/curse I believe many would be happy to live with).
I wonder how many children of famous people went on to achieve more in life than their parents did? There's probably a list.