That's the thing. A game like SMG shouldn't be rated on the strength of its story, but instead on whether the story would add anything to the game. That's why I mentioned Sonic: people often complain that they would rather just play through some levels to beat Dr. Robotnik or whoever, and not have to sit through cutscenes and horrible video-gamey voice acting. Why would a Mario platformer benefit from a strong story any more than a Sonic platformer would?
"'Casual games' are something the 'Game Industry' invented to explain away the Wii success instead of actually listening or looking at what Nintendo did. There is no 'casual strategy' from Nintendo. 'Accessible strategy', yes, but ‘casual gamers’ is just the 'Game Industry''s polite way of saying what they feel: 'retarded gamers'."
-Sean Malstrom
