I know I'll get flamed for this from the really dedicated fans, but when it comes down to it LBP just isn't that fun to play for most people. I think what the market most resonates with is that which caters to people's needs as consumers first, not what drives a medium forward.
I was a little mad 15 years ago when Tekken became more popular than Virtua Fighter, despite not having revolutionized the Fighting genre like VF did. But many years later I made peace with the fact Tekken was a lot more accessible, and to a lot of people, just more fun.
You can have it both ways, and it's been the case with a lot of games in history especially from Nintendo.. but LBP is more one than the other definitely IMO.