Well, you know, they kept the seat warm during the 70s, and in the 80s and 90s, they gave us such gems as Richie Rich, The Smurfs, Pirates of Dark Water, 2 Stupid Dogs, Super Secret Secret Squirrel, and last but definitely not least, The Powerpuff Girls - a show that survived both Hanna-Barbera the company, and Hanna and Barbera themselves.
But yeah, the Scooby-Doo clones are terrible.