title: Why is myString.IsNullOrEmpty() not built into .Net?
body: <p>A bit of an academic question, but I'm trying to understand the framework design on a deeper level.</p>
  
  <p>So we have <code>String.IsNullOrEmpty(MyString)</code></p>
  
  <p>and we <em>could</em> write an extension method to enable <code>myString.IsNullOrEmpty()</code>, though that's arguably not the greatest idea. See: <a href="https://stackoverflow.com/questions/790810/is-extending-string-class-with-isnullorempty-confusing">Is extending String class with IsNullOrEmpty confusing?</a>.</p>
  
  <p>So my question is, why doesn't MS  write this functionality as part of the .Net framework? Is there some performance consideration? And more generally, why would <em>any</em> method or property viewed as valuable enough to be built as accessible via the String object not be available as a member of any object of the string type?</p>