Because he killed you, made you stop and think, and made you either move on in defeat or find others to take him down.
Read that WoWWiki entry and tell me that it’s a ‘problem’ that Hogger could be defeating in all those different ways, including the ‘creative use of game mechanics’ tactic of dragging him to the guards.
Hogger is the definition of why an MMO is awesome. Nerfing and making Hogger solo-able is the definition of destroying an MMO because some octo-mom got her feelings hurt and would rather make a forum post than talk to another player.
Hat-tip to Longasc here for the idea.