Children, of course, never need their own room. However, I see nothing wrong with a child having his own room if wealth or circuмstances allow individual rooms to be provided. Case in point: my mother-in-law has four brothers and no sisters. As the only girl, she always had her own room, while the boys shared. I don't think it has to be limited to just situations like that either. If, for example, there is a large age gap between the oldest child and the others, I see nothing wrong with allowing the oldest to have his own room. Also, if the parents are wealthy enough to have a large house that gives each child his own room, I see nothing wrong with that either.
I guess in sum, there is nothing wrong with sharing, and there is nothing wrong with individual rooms for some or all of the children. It's up to the parents.