In the UK it’s pretty much impossible to sell any childs apparel /footwear product in the mass market unless it’s character licensed. So I’d say for me at least, it would be a must. I design a lot of kids footwear myself and ALL the product I do for the UK is character licensed.
By the way: I think you are doing an excellent job. It was a kids footwear project that I did that got me into the footwear trade!