evidence for shoes in toddlers/preschoolers?

Hi everyone,
I work in paeds and get tons of questions from parents about footwear. My personal theory (developed over 10 years of practice), is that barefoot is best as long as there isn't any foot/ankle deformity in order for the soft tissue and bones in the foot/ankle need to develop without external support during the early walking years.

When choosing shoes for outdoors I counsel parents to look for a very flexible sole and firm heel counter and to get shoes that fit the child now (not too big so they have to 'grow' into them). For indoors I recommend barefoot or a leather slipper (one brand in Canada is called Robeez) for traction and warmth. I've tried doing a literature search to see what is out there for recommendations - but haven't found anything yet. Anyone know of any published guidelines/articles?

Thanks so much!
- Amy