Yes, my question... and your opinions? Yes? No? Dont know?
It completely depends on the parenting style.
I think it is absolutely possible for parents and kids to be friends. There are many people who see their mom or dad as their best friend. I think becoming a friend to kids can be a very useful parenting technique. It opens up the relationship, creating more honesty and dialogue.
However, I think a certain line always needs to be there. Parents have the great responsibility of raising a good child that friends don't have. So they don't have the leeway to behave exactly like other friends would.