Why is there no @Html.Button in IntelliSense in ASP.NET MVC 3?

I have written my own HTMLButton extension that you can use, instead:

public static class HtmlButtonExtension 
{

  public static MvcHtmlString Button(this HtmlHelper helper, 
                                     string innerHtml, 
                                     object htmlAttributes) 
  { 
    return Button(helper, innerHtml,
                  HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes)
    ); 
  }

  public static MvcHtmlString Button(this HtmlHelper helper, 
                                     string innerHtml,
                                     IDictionary<string, object> htmlAttributes)
  {
      var builder = new TagBuilder("button");
      builder.InnerHtml = innerHtml;
      builder.MergeAttributes(htmlAttributes);
      return MvcHtmlString.Create(builder.ToString());
  }
}