@ OP - You ask why SMG sells so much better than LBP. I can answer this honestly, without taking sides. The Mario franchise is Nintendo's oldest IP, arguable only against Donkey Kong. Are the newer Mario games better than the older ones? It is also arguable. What is undeniable is that people recognize the games, get nostalgic for the characters and so forth. I think this is the reason why I enjoy Zelda: Twilight Princess so much - it truly feels like a continuation from my favorite all time game - Ocarina of Time. It gives me the nostalgia of the old game, with updated technology and story.
Now, with LBP, for as much advertising as Sony can throw at the world, Sackboy and friends are unknowns. They are the new kid on the block. They have to earn their stripes, find their way into the hearts of gamers, and continue to grow with sequels. There's always that ONE game in a series that makes you fall in love with the characters. Not everyone was sold on Mario with Super Mario bros. Hell, it took me to the 5th official Zelda game to truly love the characters.
LBP will just have to be continued and not analyzed by sales, but grow by being ever-present and growing in personality to attract more gamers. That is on the developer and publisher combined. If they just look at sales and say "well that's a failed IP", then they have turned their backs on their beloved creations.
I know that I could never do such a thing. The world doesn't know Gaevan (pronounced Guh-vin), but I do, as he is created from my mind and lives within my heart. Someday the world shall know who he is in one of our dev team's future games. Yet, I will never dismiss him by sales numbers. I will just try harder and harder until the world accepts and loves him too. There is a difference of being a salesman and being a game designer. Let's hope that the people behind LBP are not salesmen.