What a lot of people forget is that in the 80s/90s (we'll call it the Jordan Era), NBA was like a religion for many many people, especially the youth. It was every where and that was when it was at its most exciting. MJ was the top of the mountain, but that was an era that produced Hall of Fame caliber talents and stars with cross promotional appeal like it was it was the easiest thing in the world to do. I could sit here and talk about many stars and many great careers without having to mention MJ once.
Even the bad boys of the NBA, like Dennis Rodman and Isaiah Thomas, were fun to hate in their own way.
Right now, LeBron James is the biggest star in basketball, and the sport's greatest talent, and has been for years, but that is in an era where I bet if I went on the street and asked people to name 10 NBA players besides him, only the most die hard of NBA fans left would be able to do it. The caliber of star of talent just isn't what it was during MJ's years, and the game has changed too.
With that in mind, the original Space Jam, for all its faults, was a movie that capitalized on something huge: The NBA was HUGE back then, and using cultural icons like The Looney Tunes and the face of Americana, Michael Jordan as the leads, it was the perfect "Product of the 90s" movie. Trying to replicate that in an era where the NBA is nowhere near as interesting or exciting just seems a fool's game to me.