Babies are supposed to wear soft soled shoes when they are learning to walk, right? What are the developmental reasons for that? At what point are they supposed to switch to regular soles?

I have a 6.5mo who is already crawling and getting better at it every day. (This is terrifying, but that's a separate topic!) I have the feeling he might be an early walker because is just so damn eager to do it. I need to figure out how to keep his feet warm during the winter in northern NJ.

Suggestions for cute, warm, age appropriate footwear are welcome!