Is Inheritance really needed?

class Point( object ):
    # some set of features: attributes, methods, etc.

class PointWithMass( Point ):
    # An additional feature: mass.

public abstract class GeneralPresentation
    {
        public GeneralPresentation()
        {
            MenuPages = new List<Page>();
        }
        public IEnumerable<Page> MenuPages { get; set; }
        public string Title { get; set; }
    }

    public class IndexPresentation : GeneralPresentation
    {
        public IndexPresentation() { IndexPage = new Page(); }
        public Page IndexPage { get; set; }
    }

    public class InsertPresentation : GeneralPresentation
    {
        public InsertPresentation() {
          InsertPage = new Page();
          ValidationInfo = new PageValidationInfo();
        }
        public PageValidationInfo ValidationInfo { get; set; }
        public Page InsertPage { get; set; }
    }