There are a few good reasons to use craft kits like it saves time, it builds up your children's imaginiations as they create a different item each time from the same material, it all comes together in the same box and many more reasons.
My main reason is probably a combination of all the above factors and is called convenience.
If you are anything like me, (which of course you are not!), you do not feel particularly creative when it comes to art and drawing and things like that. Drawing a stick figure for me can sometimes prove to be a challenge. You are probably surrounded by friends who talk about the art projects they undertake with their children and you feel slightly underwhelmed by your efforts. They say things like "it's so easy to do bla bla bla" You just sit there thinking "for you, maybe!".
I assure you this is even more of a problem when you home educate as all your fellow home schoolers are soo much more creative and imaginative than you (at least, that is the way you feel).
Your brain just does not really understand how to make anything look nice without strict instructions to follow. You know you have done it in the past but somehow you just cannot create masterpieces at the moment and definitely not with your children.
If this in anyway describes you, then have no fear, there are numerous craft kits out there for you and your children to enjoy. And thankfully, it might even help them learn to be imaginative and creative themselves without too much input from you apart from the congratulations and help with non-child friendly tasks.