Wow, Sandman and Lizard are such lame villians. Also, though no one will agree, Carnage is a lame villian.
I believe Carnage was created soley to capitalize on Venom's popularity. This way, Venom could be marketed as a 'good guy' with his own series (or series of mini-series). Venom works so well as a villian, he should stay that way. His 'comeback' from a few years ago set him back in his villianous ways, and the world was put right again.
'Maximum Carnage' is one of the many, many reasons the '90s were the worst period in comic history, along with 'Age of Apocolypse', 'Onslaught' and the horribly written 'Death of Superman'.