Showing Anakin and Obi-Wan’s friendship makes it way more devastating when Anakin turns and they have to fight. I think that’s more important then showing him as a young kid.
Showing an innocent child who turns into an inhuman monster who kills children is very impactful as well, and showing Anakin’s childhood and his life in slavery is important to understand his character.
As I said, everything in the Prequels is important, the problem is just that there’s a limited amount of on-screan time, which prevents you from showing everything in detail. That’s why I said that the Prequels would have worked better as EU. I mean, imagine if the Prequels were an EU multimedia project, consisting of books, comics and video games. It would have been great, because in a EU multimedia project everything can be shown in detail and you don’t have to worry about on-screan time at all.