My friend had absolutely no arches in her feet, she had to wear speacial padding in her shoes to correct it. She walks kind of like a duck and her feet look wierd but there isnt any serious risk beside wierd walking
I don't have that many problems, but i have serious flat feet. They look a bit weird and I have a 300% accelerated chance of arthritis in my knees, ankles, and feet when I'm old....but that's really it.
i wear inserts in my shoes because i have no arch whatsoever in either of my feet. if i dont wear them, my feet start to hurt real badly. also if i dont wear my inserts and walk for a long time, my ankles can start hurting too.