How Come The Undertaker Has Never Been Pushed As The Number 1 Face In The Company?

Anybody here notice that during The Undertaker's long WWE career he has never been billed as the number 1 top face where they built the entire company around him. There was always some other face that Vince paid more attention to whether it be Hulk Hogan, The Ultimate Warrior, Bret The Hitman Hart, or Shawn Michaels during the Federation years or Stone Cold Steve Austin and The Rock during the Attitude Era or John Cena and Triple H today. I can't ever remember The Undertaker being put in a position where he was by far the number 1 franchise that was the face of the WWE. He always played second fiddle to some other main event face on the roster who sells more merchandise than The Undertaker.